If you want to be stealth, and there are several guards, do this. If some guard patrols to a lonely area, use the tranquilizer gun and shoot him almost at the top of the boot. The worst reaction he should get if you hit the right spot is: Huh? He will look around and then keep walking. If you time it right, he will go to the lonely spot and fall asleep. !Bon Appetit!
How to defeat the boss easy!
Near the end of the game
I found this to be one of the best ways to defeat the boss. Put on the best camo that matches the terrain. Then kneel next to a tree but still in the white area. Take out your sniper rifle and eventually the boss will come looking for you. Shoot her and duck behind the tree because she will shoot at you and probably run after you. When she gets close, put your weapon away and (for me, hitting almost all the buttons). When she loses grip of you while she's trying to perform her CQC, hit her a few times to knock her over. Then unload on her while shes down with a machine gun and go hide again and repeat this method until she dies.
after you win against Colonel Volgin in a fight
After you shoot the C3 charge that EVA planted on the bridge, you fight the Shagohod at this place. Equip the RPG-7 if you don't have it equipped already. Now you fight the Shagohod alongside with EVA. To damage the Shagohod, shoot the inner treading (using the RPG, underneath the part that Colonel Volgin is inside) and wait till EVA drives behind it and fire at the back (with the RPG) where Volgin is inside. To evade the missiles, Take out a machine gun ( I recommend the M63 ) and fire at the Incoming missiles. After you defeat the Shagohod, Volgin controls the Shagohod Manually. You will have to finish him again. If you are fast with the sniper, you can shoot him while he is chasing EVA. After you defeat him, the game's still no over yet....
Getting out of Grozjn Grad Jail 2
Puke to get out. To puke go into CURE and spin around heaps. Get out of CURE and get to the game. When the guard enters, tap on the cell bars to get his attention and use the fork to kill him.
Get Out of Groznyj Grad Prison Cell
If you talk to Sigint enough time while your in prison, he tells you that the cell door is unlocked by a certain frequency. If you "knew" the frequency you could unlock it with your radio. That frequency is 144.75.
At any time during game play, on the second part, Snake Eater, go to your codec menu and tune to station 140.73, and call it. This will call in fire support but you will not be allowed to do this more than once. Because the station will not be used again. Believe me, I saved my game, then used it just to play around and then shut it off. Then I went to use it again later and it wouldn't work. So, do not use this unless in dire need.
More Stuff Before You Start Your Mission
After Snake goes back to the jungle the second time, Major Zero will tell you to head North. Well, instead of heading North, go South. There are NO enemy soldiers on the way back, just a few snakes and crocks! But anyway, go all the way back to where you started the first time to find some good items, and a certain flower that can come in handy. You will need to cut it from the ground to obtain it. This is no cheat, it was just my luck of going the wrong way, and I was able to find more things. You can easily find your way back to where you need to be. Just follow the path North again. Easy stuff.
Surviving "The Sorrow"
When the game over Screen comes on use the REVIVAL PILL... If you've died at least 3 times in this part, Call anyone on your Codec and they will tell you this.
There is a way to get food without shooting them or stabbing them with your knife!
all you have to do is execute the cqc (close quarters combat) by pressing the  button rapidly near a snake, mushroom, ect. This combo can also be done in FPV(first person view)also this can be used to wake up sleeping guards that are on the jungle floor.
How to Find Kerotan (the frog) Easier
After the night at the factory in the snaker eater mission in the swamp beyond the electric fence area, swim through the swamp across towards the exit when you reach the land go to the right their will be a shallow area, walk around and you should find the GA-KO uniform, putting it on will let you here the frog. Its gets louder in the direction its in, (call Sigint for a funny conversation with him, you and Para-Medic).
Defeat The End Quicker
When you began the boss fight with The End, The legendary sniper, go to your map and find all the sniper location points. You should have some TNT explosives in your weapon inventory, so bring those out. Along the way at each sniper point, set a TNT charge right were the End would lay in prone and snipe you. When you put a charge on EVERY single sniper point. Attack the End. When he runs to another sniper point, pull out your TNT charge dentanator and blow the first TNT. If he doesnt lose health press the detanator again and agian until you hit him.
140.01 - Salty Catfish / 66 Boys
140.52 - Rock Me Baby / 66 Boys
141.24 - Sea Breeze / Sergei Mantis
142.94 - Pillow Talk / Starry.K
144.06 - Jumpin' Johnny / Chunk Raspberry
147.08 - Surfing Guitar / 66 Boys
147.59 - Sailor / Starry.K
149.53 - Don't Be Afraid / Rika Muranaka