Well Steve, i dont know how long you have had it, so i will assume that it is a new aquisition.
1. Give it a thorough clean, inside & out. This will allow you to see what it is you really have bought. If you are still happy with it, then.
2. Give it a complete service & tune up. This way, you bring your variables under control. After this, you will KNOW about the mechanical condition of the car.
3. Cary out any minor repairs that you found necessary during the service. Brakes a bit worn? Now's the time to fit new linings. A trip to the wreckers will often turn up many of the parts you need, like lenses, knobs, trims etc.

Now you will have a clean, sweet running stocker. Check out what wheels are available. A set of 13" mags will dress it up very nicely & you will have a good street hack that awaits your further attention.

There are lots of options, like, A14 / A15 engine upgrade, paint, interior, further engine mods & lots more. Just make sure that the body shell is sound, & worth the effort before spending any real money in other areas. If she's straight & sound, the sky's the limit. Keep tuned to this site for lots of ideas.
Chris