Before going to an auto repair shop, you should already have a good idea as to how much a specific service (ex. oil change or brake job) would cost you. Look for a reliable online resource that will provide you with a fair estimate on prices of auto repairs, parts, and labor. Hence, you can avoid shops or mechanics who are out to rip you off.
One such website is Repairpal.com From the website, you can find a local auto repair shop that offers the exact service you need and is nearest to your location. For instance, if you live in Houston, you can simply type in your ZIP code and car make (ex. Acura TL) to get a list of Houston auto repair services. You will also be able to read reviews and ratings from customers of each shop.
The website also provides a bulletin board where you can read tips and information on how to deal with common car problems. You can also post your own question to get specific answers from master technicians. Lastly, you can store all information for all vehicles you own so it would be easy to keep track of all previous repairs and services.