Finish the game and save Chris or Jill you will get the secret key. Then 
when you finish the game save it and then load the saved game next time and 
you will start with the seceret key which gives you the other clothes for the 
person you finshed the game with last. All you have to do next is find the 
locked door its in the house. 

If you finish the game in less 3 hours, when you start again you get a big 
rocket launcher (unlimitted ammo) you destroy all monsters in one shoot.

Start the game with Jill. When to go off into the dining room, walk back to 
the main hallway. Wesker will say "go investigate that shot." Go back to the 
dining room and Barry will say "where did you go?" Walk by the Grandfather 
clock and a zombie will appear. Barry will shoot him and curse at him. Go visit 
Kenneth (the place where you met the first zombie) and he will have no legs 
or clips. The game is to "be easier".

Here are some cool game shark codes
Infinate health: 800c51ac0060
Start with flamethrower: 800c8784ff06
Start with rocket launcher: 800c8784ff0a

There are 2 rooms with numeric keypads. One of them is the room that contains 
the bottles and the chemicals to make V-Jolt. The code to enter the room is 345. 
You will find the 4 bottles to make V-Jolt on the 2 shelves in the room. There is 
also some writing on the wall inside the room, make sure you read it.

To enter the weapon screen anytime in game quickly press R1, R1, R2, R2, 
Left, Left and x, x. Remember do this really quickly and you will have a zombies 
head and a rocket launcher.

For Game Shark Users, use the following codes to obtain the respective 
items/weapons in the chests:
800C8724 6403 (SHOTGUN)
800C8726 6405 (COLT PYTHON, MAGNUM ROUND)
800C8728 6408 (BAZOOKA, ACID ROUNDS)
800C872A 640A (ROCKET LAUNCHER)
800C872C 6441 (FIRST AID SPRAY)
You should have 100 units of each item (e.g. 100-round shotgun, etc.). 
Remember to turn off your game shark/action replays once you have 
confirmed that you have these items, else you might encounter problems 
when picking up other objects.