Picture trick:
If you take a picture of the bare chested man located on the locker in the engine room, when you get to the Metal Gear Ray room, the Marines will have forgotten their trousers and will be wearing boxers only.

Guard from Shadow Moses:
After you gain access to the directional microphone in Shell Core 1, B2, proceed to find Ames like the cyborg said. Once you find Ames (he is sitting next to the only table with boxes on it.) and begin talking to him, you will be told to listen in on a conversation between Shalashaka (Revolver Oceleot) and "Solid Snake." Once the screen changes into the Directional Mike mode, turn to the right. If you search around enough, you will point towards a bathroom and hear a guard talking about his experience at Shadow Moses.

Getting the dog tag:
To get the dogtag you need to sneak behind the solider & point your gun at him, with the L1 pressed go in front of him & search his chest, he will drop the dog tag if he had one (you will notice the dogtag when you see shining spot in his chest) & he will drop more items if you search him more.

Other dogtags:
When Olga & the president are dead, shake their bodies to obtain their dogtags.

Getting past the mine areas:
If you don't have a mine detector & you entered a mine area the best way to get pass it is to crouch all the way & you can collect the claymores as well!

Easy way to defeat VAMP:
Sleep on the ground behind the pool fence & equip your m4 when he get too close to you, just before he shoots you shot him in the fps mode & repeat that until you beat 'em up!

Easy way to find Ames:
Use the book to draw the guard away then take your time searching.

How to get the game bounes:
Finish the game on extreme mode with all the dogtags & you will get the bandana (inifnte ammo), digital camera & the stealth camo.

RAYs battle:
In order to destroy the RAY you will need just some CHAFFs & a stinger, get close to it & don't fire until it opens it mouth to attack you with the rail gun. This will take more damage on it.

Thermal goggles:
When you defeat Olga go up on the roof & climb the tower. You will find a thermal goggles, use it to detect mines & laser beams.

Control the camera during Cut-Scenes:
Will in a cut-scene, press R1 to zoom-in, use the right analog stick to move the camera around.

Stronger Grip:
Do 100 pull-ups to raise the grip level.