One thing not yet mentioned is that you have to like doing it... at least like it enough to feel good about the savings from doing it yourself. If you don't like doing it, all bets are off.
All us DIYers scrape our knuckles, wrestle with bolts that won't budge, and invent new swear words, but once we wash our hands we have a feeling of accomplishment on a job well done and feel good about the money we saved. That's what separates us from the people that would rather dish out their hard-earned money to have somebody else crawl under the car.
95 E320 Cabriolet, 131K