Weapons Guide: Know your weapons!
There are many types of weapons in the game. Here I will tell you which ones are best in certain situations and which ones you need to be careful with (when used by enemies). The main types of weapons in the game are these:
Melee: Your melee weapon. Access it by pressing Q. Pretty weak but good for finishing off almost dead enemies if you don't want to waste ammo.
Handgun: Very common at the start of the game. The handgun is pretty weak, but not as weak as your melee weapon. All of them are semi-automatic, with a variety of strength and fire rate. I ussually prefer not using handguns, but it's unavoidable at the start of the game. The Bren 10 is acctually a pretty powerful weapon. It will do nicely if nothing else is on hand.
SMG: The sub machine gun. These have very high rates of fire, but are ussually weak. The MP5 is pretty useful early on, but as more weapons become available I advise that you stop using these.
Magnum: Some of the most powerful weapons in the game. The magnums are great if you can get enough ammo for them. They deal enormous amounts of damage, in normal mode a headshot with the Desert Eagle will instakill. Magnums also have pretty good fire rates.
Battle Rifle: These appear about 1/4 of the way through the game. They are alot more powerful than the SMGs, but they have a slower fire rate. There are more types of battle rifle than any other weapon, and they take various types of amuntion. Your first choice when choosing a battle rifle is the SOCOM, which has a high fire rate and deals very high amounts of damage. It also uses the WIN ammo, which is fairly common. The SOCOM doesn't appear until you are about halfway through the game. Your second choice is going to be the HK 91, which is basically a weaker version of the SOCOM. If niether of these are on hand, go with the weaker but faster-firing AK-47.
Shotguns: My personal favourite, other than the special weapons. Shotguns can be truely devestating if used correctly. There are three types of shotgun; the Benelli, the USAS-12, and the Pancor Jackhammer. While using a shotgun, you want to get really close to an enemy and blast them, getting an instakill. Shotgun ammo can be hard to find, but I highly reccomend using a shotgun if one is on hand.
Gauss/Flechette Weapons: These are the weapons that pierce multiple enemies, wounding or killing everything in their paths. There are many types of these, and they include the laser cannon, a high-powered slow-firing weapon that can kill many enemies in one shot, the gauss pistol, which has a very high fire rate but doesn't do that much damage, the X6 Flechette Rifle, the only automatic flechette/gauss weapon, the gauss shotgun, it has the slowest fire rate in of any weapon, but it is extremely powerful, and the Hades Rifle, which basically kills anything in its way.
Grenade Launchers: I ussually prefer not to use these, as they are hard to aim, have limited ammo, and a very slow fire rate (with the exception of the bean rifle, but that has limited range). None the less, these re very dangerous weapons that can take out many enemies in one shot.
Defensive Tactics: Here is a list of the order in which you should kill enemies.
1. Shotgun
2. Magnum
3. Battle Rifle (SOCOM)
4. Flachette Rifle/Gauss Weapons
5. Grenade Launcher
6. Battle Rifle (others)
7. SMG
8. Handguns