Gang bosses strategy
Los Muertos:

Juan "El Numero" Martinez:
This boss is best approached from the surrounding rooftops as there is a lengthy and well guarded climb from the bottom of his appartment complex otherwise. When you reach him at the top of the building, he will be poorly guarded, and an easy explosives take down.

Jose "Tremendo" Guerra:
Guerra is too easy, you can just swim to the hidden hole at
the bottom level of the nightclub, jump up, toss in a nade or two towards him,
then shoot him till he falls.

Rafael "Chuco" Diaz:

The easiest way of taking out Diaz, is to go round the back of the garage. Take out any gang members that get in the way. At the back of the garage is a pipe. Inside is a Hidden Orb. Jump inside, get the orb, and then drop down. You'll drop into an enclosed room, where you're safe for the time being. On the other side of the doors is Diaz himself. Kick down one of the doors, just one. If you kick down both, gang members will easily get to you, so having one door left provides cover for you. From here, shoot and bombard Diaz with grenades until he's dead. Then escape back up the pipe.

Rodrigo "Montana" Alvarez:

The quickest and easiest way to do this is to go along the beach towards the sports complex. Climb the rocks, and from there snipe the gang members that will get in your way. Once you've taken out the ones which will pose a threat on your route to Alvarez, jump down from the rocks and make your way to the circle of rocks where Alveraz is hiding. Shoot him and throw grenades until he's down. Then pick up his grenade launcher.

Ramon "Pistola" Gonzalez:

Gonzalez isn't as hard as you'd expect. Approach the lighthouse from the road leading to it. Don't go to the main gates, but jump across the rocks and over the water. Gonzalez is on a little platform at the front of the lighthouse. Jump up the rocks to the right of the lighthouse, until you're level with Gonzalez. From here, lob grenades from the grenade launcher, and throw a few up too, to finish him off.

Violetta "Santo Maria" Sanchez:
''Santo Maria'' is much like Juan Martinez, she has almost no cover where she is stationed,
so just climb her building and blast her to bits with grenades.

Don Domingo "El Brazo" Garcia:
Well it is the kingpin so the first thing you should do is taking out all the generals.
Then one thing you could do is swim under his villa, there is an entrance you can take. Make your way up to him from here, once you get to Garcia, carefully throw grenades into where he is. He will easily get hit. Don't throw grenades when you're in there, as there's nowhere to run when they explode. Once he's dead, quickly get away whilst running to the back of the villa and jumping into the sea. From here, swim to the main Los Muertos area again and take out the Final Crime.

Volk:
Sergei "Sovetnik" Yuriev:

Yuriev is one of the most complicated Generals in this game to kill. Cause you will kill everyone and Yuriev will still be in his damn tower. But all you have to do is blow up 3 switches or control panels and the doors to Yurievs tower is open. The 3 switches are placed around the tower. One is the near the front of the tower, above some pipes across the tarmac. The other two are round the back, on the large frame building. Blow these up, and Yuriev will be released onto the roof with a few of his men. Take out the men and then focus on Yuriev with grenades and gunfire.

Igor "Rafik" Biragov:

From the supply point near Biragov's building, jump down onto the roof of his building. From here, jump down, and take out any men that oppose you. Head into the small section where Biragov is. He's at the top of the room, running around. Lob grenades up to the balcony bits, to get him down. Shoot/kick him to death, or keep throwing grenades.

Natalya "White Fox" Gryzunova:

Gryzunova appears in two places. During the day, she appears at the Observatory. At night, she's in the marketplace in the main Volk section. If it's the day, make your way to the Observatory gates. Kick them down, jump up the right side of the observatory. Gryzunova is on some steps at the front of the building. If you have a rocket launcher, let some rockets off towards her. She'll be dead in seconds. If not, throw grenades and shoot her until she's down.

If it's night, jump up to the roof around the marketplace. The marketplace has glowing green lights running around the edge. From here, let off rockets or gunfire towards Gryzunova and her men. Again, it won't take long.

Boris "Baron" Mikhailov:

Mikhailov is in a big ship. Firstly, get to the ship. On the left side of the ship is a yellow crane. Jump up to the lower rung of the crane nearest the ship. From here, jump towards the edge of the ship and climb on board. Mikhailov is in the drivers area of the ship. Go up the metal steps leading up there. Take out any men you come across. In the drivers area are some men with Mikhailov, who come rushing out a few at a time. Take them out. Lob some grenades inside to get him down, then kick or shoot him to death.

Viktor "Curse" Rabotnikov:

Rabotnikov is slightly off shore. To the right of his rocky island is an easy way in across the sand. Approach from the right hand side, and you'll be in amongst the dunes. This supplies cover from any fire you come under. Take out any men shooting at you, then jump over the first wall. Run along a bit. Rabotnikov is right at the back of the island, behind some rocks. Get above him. Throw grenades down to kill his men and damage him. Then finish him off with more grenades/rockets/gunfire.

Olga "Meat" Romanova:

Romanova is in a quarry, and a pain to get to. Rather then go through the main entrance, climb up the rocks a little way to the right of it. From here, pick off any men posing a threat to you. Be careful, they are armed with rockets. Once all threat is eliminated, run to the other side of the quarry, making sure to take out any men in your way, and trying not to get blown up. At this side, is a track gradually going up. Jump up these rather than going the long way. Once at the top one, run along to the end on the right hand side. You'll get to an entrance. Inside is Romanova and some men. Don't enter straight away. There are explosives and chances are stray fire will blow them up taking you with them. Stay outside, throwing grenades towards the men. Once they're down, focus on Romanova. Take her out however you see fit. Weakening her with grenades is a good way to take down easily.

Vladimir "The Wolf" Golyak:

Golyak is fairly hard to reach. He's right on top of an oil rig. Out at sea. Follow the large pipe in the sea to the first floating platform. Take out the men here, then run along the pipe leading to the next big platform. Take out the men on the first floor. Then run to the left, then round the corner. You'll get to a gap. Jump this and land on the other side. From here, run round the corner and go up the stairs. Keep going up the stairs until you see a bridge type walkway up to the main rig. Run up this. Be careful, as the gang members throw barrels down and then shoot them. So get up there quickly. Jump straight ahead once up. Jump up the other side. Take out the men here, then run round and up onto the helipad. From the helipad, shoot rockets at Golyak, or take the stairs and jump up to where he is to shoot him or kick him. Once he's dead, just jump off into the sea below and swim back to shore.

Shai Gen:
Melissa Fang-Yin:

Fang-Yin is in the Intel Center. From the supply point next to her location, jump onto the large circular building. From there, jump to the lower one next to it. From here, take out any gang members you see. Then jump down and make your way to the entrance just a little way along. Go inside. Work quickly here. Run up the stairs till you see Fang-Yin. Then quickly throw grenades and shoot/kick her till she's down. Then quickly run out. There's very little room inside, so speed is important to keep yourself alive.

Mrs. Timbol:

From the supply point near her location, jump down the tall buildings on the right of her location. Timbol is right in the center. Let off rockets/gunfire at any gang members in the area. Timbol can sometimes run out of the building she's in, so if she does, let off rockets/gunfire at her until she's dead. If not, jump down and run along the walkway to her little enclosure. Throw grenades inside to kill the men and weaken Timbol, then finish her off.

Vitaliy Rzeznik:

Rzeznik is very easy to get to, and if done right, you will fight no-one but him. Firstly, climb the rocks at the side of the building, near his location. Then jump up onto the roof from here. Once on the roof, head to his location. There'll be some steps down. Run down, and go into his room. Wow, no-one there but him! Work quickly, throw grenades and shoot him, then finish him off however you see fit. Then run back up the steps and jump off the roof and into the water.

Thadeous Oakley:

Oakley is fairly easy to get to. You could walk down the underground tunnel into the expo center, but just outside there are 2 Shai Gen cars. Drive down the tunnel, hitting the guards as they jump out to shoot you. Thus, you get driving skill points while you go faster to your target. It also doesn't hurt that your enemies are dead on the way out. Once inside the building, take out any men you need to. Round the back of the center building, jump up onto the bridge leading inside. Take out the men in the first section. Then go to the left and throw a grenade through the door. This should take out any men inside, if not, take out any survivors. Do this for each room till you come to some spiral stairs leading up. Take out the men at the bottom. Then run to the top. Once there, quickly head through the door. Oakley is at the top of the building on a balcony. Jump to the center and throw grenades up to him or rockets. Keep doing this till he's down. Alternatively, you could jump up to him and kick him to death.

Dr. Baltazar Czernenko:

Head to the research lab from the nearby supply point. Take out the gang members in front of the entrance gate. Blow down the gates, then head left. There are some men behind some grates. Throw a grenade there to take them out. Behind them are some steps down into the building. Once in, take the stairs up. Czernenko is inside one of the rooms round the side. Blow down the door that leads to his room. Take out the gang members inside. Czernenko is down the end of the room, so throw grenades at him and kick or shoot him till he's done.

Colonel Axton Cowell:

Cowell is in the fairly tall tower with a red dome on the top. He is inside that red dome. At the front of the building, kick down the doors at the front. Take out any gang members. Then head towards the lift. Activate it, and take out any men until it arrives. Get in and ride till it stops. Get out. Don't focus on the gang members here, just keep running, to save time. Run up all the ramps, until you reach the top. There'll be an opening onto the front of the tower. Don't look down, it's a long way to fall! To the right are some ledges you can climb. Once at the top of those, take out the men there. Then jump up to the red dome. Cowell is inside with a fair few men. Throw grenades inside and finish him off with a few kicks.

Zuang Lun Wang:

Wang is the kingpin, and in the tallest tower in the Shai Gen area. He is pretty hard to get to also. Climb up the Epicenter north of Wang's tower. Climb on top of the Epicenter sign, and climb the side of the building using the windows. Move towards the corner of Wang's tower. Take out any guards here. Move to the edge of the roof now. Carefully jump from the roof to the ledge of the tower. Follow the wall to the right, which leads to an open passage taking you straight into the tower. Take out any guards you need to. Try and use headshots to save ammo for further up the tower. Take the stairs up to the next level, where there are plenty of guards. Jump up to the steps above you, and run up as far as you can go. Near the end of the highest you can climb by steps, is a black bit of structure. Jump onto it, and from here jump onto the steps from the other side. Then go up the steps further. Here, there are five lit rectangular bits hanging from the ceiling. Jump to the one on the side of some more steps. Jump up, then jump behind you onto the steps. Take the stairs up. This room has some big yellow cylinders hanging from the ceiling. A little above is a walkway. Below this are several openings. Jump above these and cling onto the edge of the wall, then jump from here up to the walkway. Keep going up the steps until you can go no further. From here, jump onto one of the yellow cylinders. Jump across the cylinders until you reach steps up to the next level. There are few enemies here, so take them out one by one as needed. Go up the stairs on this floor, they're wooden. This takes you to the roof, where Wang is. Equip the rocket launcher, target Wang, who is on the balcony of the gazebo, and blow him up with the rocket launcher. Continue your barrage until he is down.