Far Cry 2 is best played as a sniper game. Seriously, it's pretty much the consummate sniper game. A lot of times, running into a firefight with an automatic will get you incapacitated very quickly.
I highly recommend going with only a few purchased (and upgraded) weapons. Don't waste those diamonds on guns that just aren't really practical.
- Sniper rifle (upgraded) as your primary. There are a couple of different models depending on which stage of the game you are playing. Upgrade to newer models as soon as they become available.
Act 1: Stick with the M1903 sniper rifle (upgraded). You might be tempted to buy the SVD, but it does less damage and is less accurate, despite having a larger magazine capacity. Save those diamonds for the awesome AS50 (available in Act 2), which makes the game a good deal easier.
- Secondary weapons- Look to a reliable pistol in Act 1. In act 2, get the Uzi as soon as possible. Very useful backup for a sharpshooter.
-Special weapons- rocket launchers and light machine guns (PKM, M-249). The rockets, naturally, for destruction and wiping out convoys and vehicles. The light machine guns are excellent backups for a sharpshooter. I alternate between these two depending on where I am, and what I'm doing next. However, once you get the Uzi, the light machine guns become less necessary, so one can keep a rocket launcher on hand at all times.
Others of note (should you have the diamonds to buy extras):
- Ar-16 assault rifle. Lovely dot scope and a very tight/accurate burst fire.
- FAL assault rifle. No scope, but more powerful and reliable.
Tactics:
- Distance! Park your vehicle quite a way from a checkpoint/hostile area. Jump onto the hood and snipe. Mount the turret when necessary (great for cleaning up mid-range/stragglers and saving your ammo), but be careful if the enemy closes distance, or vehicles approach. Use launchers on charging vehicles.
- Learn how to quick switch between driving and turret, and when it is safe to do so, or when you should exit the vehicle to engage the enemy.
- Use fire to flush out enemies, but be cautious in doing so.
- Get any diamonds you can, or that are not too inconvenient.
- Download the patch to address the corrupted save file issues that plague the game. If you can't get access to this patch, DON'T SAVE WHEN PROMPTED AT THE END OF CERTAIN MISSIONS. Only save in safe houses or weapon stores. Don't overwrite saves- this may take up a chunk of your hard drive, but it means the difference between replaying 30 minutes or 4 hours, should you experience a corrupted save.
- Shoot everyone that you can in the face.