How do I make it last?

I am 15, and I recently bought my first car by myself, a 1983 Volkswagen Rabbit GTi, completely stock, with 216,000 miles on the engine. As far as I know, it has never been rebuilt. It is screaming at me for a tune up, and I was wondering what all I should replace at this point to squeeze the most miles out of this aging engine as I can. Along with parts, if you could include good brands, I would appreciate it. Thank you!