Get more time in Hang Eight and the Plant Food levels where you have to race against the clock for a gem by entering the Bonus area and then purposely failing by jumping off the side of the platform. You will then restart in the level with more time than you were given at the begining of the race.

Free Aku Aku Mask at Start of Levels:
As soon as Crash goes throuh the portal hold down R1 and X

Skip 1st Level:
If you skip the first cutscene you won't have to play the 1st level and will go directly to the first Warp Room.

View Secret Ending:
Get 100% Complete