As the others have said, the maintenance stuff like check DV valve PCV etc. Mind and check the cabin pollen filter, under/behind glove box as it is often not changed and gets pretty minging!
Other good cheap mods are things like interior LED's, LED number plate lights, Stubby aerial, seat adjustment badge inserts...
More expensive stuff like exhausts, bumper/trim colour coded or even go for r32 rear bumper and exhaust, remap, air intake, get it detailed, upgrade engine mounts... depends what you want from the car...
There are literally a million things you can do to mod a car, have a look through the other members rides threads and see what you like and don't like.
Chris