i) Ensure you are familiar with the game. You don't want to waste time wandering aimlessly.
ii) Skip all FMVs. Open the disc cover/tray and close it again to skip.
iii) Skip through all dialogue. Change the text speed to maximum and mash X to get through it quickly.
iv) Avoid all non-essential ATEs.
v) Try to avoid as many encounters as possible. If you feel you're taking too long to traverse an area, soft-reset and try again.
vi) Save often and in as many slots as you can.
vii) Save before entering a shop. Plan what you are going to buy first, then reset and complete the transaction as quickly as possible.