Whenever you see barrels on a corner, do not blow them up. You must jump on them. Jump from the barrels to the rooftop and to another rooftop until you see blades. Go over there and to the building. You can now usually finish the mission easily. Save the game. You will fight a swarm of Somalis. If you die, reload the saved game and try again.
-Unless you are a sniper, always stay on the move.
-When playing as a sniper, finding a good hiding location is vital. Try remaining near an area with a lot of brush or shadows so you are not as visible. If you do not want a high powered rifle in an urban area, try the M21. Otherwise stay with the .300 Tactical or Barrett.
-Remain stealthy if your team is losing and you need a PSP. The enemy will likely be distracted by the rest of your team.
At the final stage of the mission, you must destroy a ship. In the bunk hold of the ship, there is a man with an AK-47. He will be watching for enemies. Instead of killing him, jump over him. He is not shooting at you. You can jump in front of him or fire beside of him. He will get down, but not shoot at you.