To make the biker version of the costume, here's what you need:
A wash out faded blue jeans A plain body fit white t-shirt A bomber-styled leather jacket A pair of rugged black boots Aviator shades
Just wear all of these and you're good to go.
If you choose to pull off the fighter pilot costume, just replace the jeans and the jacket with a green jumpsuit with some patches. Of course don't forget to wear the iconic aviator shades. There are also other characters to choose like Iceman (Val Kilmer). Should you choose to be like him, all you need is a blonde hair to go with the rest of the pilot costume.