Wise woman say: always buy repair manual to car.
That way, at least you can read what is going on and not get completely and utterly screwed. It is the best $30 - $50 you will ever spend.
Oh, and second corollary: make friends with people who know how to fix cars.
Once in a great while, you will make a mistake, but you learn from them. Most of the time you will save yourself a buttload of money.
Try, try again sez I. (You can send me what you save :-D)