Painting a car is 95% prep and 5% painting. You pay a lot for professional paint jobs b/c of the preparation and paint costs. Usually it is just the preparation.
What you need to do is pull out all the dents/dings. Fill in all the holes, and bondo any damage. Sand until smooth and make sure everything is even. You dont want low spots or high spots. You dont want uneveness. Primer, sand, wetsand. If this is all done right the paint job will be rewarding.