I have a 1984 honda prelude and I would like to know what kind of modifications I can do to it...

Engine, body, something else - and for what purpose?

You can put new wheels on it.
You can "tune" it.
You can't paint daisies on it.
Really... it's your car... do what you want.

Depends on how much money you have. Turbo, Nitrous, etc. But you will still have a car that is almost 30 years old and have minimal value.