Any tips for buying used car for a first timer?

I've been reading some of guides, but I still feel uneasy with going through the correct process of buying a used car. I'm a 20 year old college kid who is in need of a used car now to get between school and a part time job.

The most personal guide I've been able to read up on to buy used cars is this: http://www.reddit.com/r/cars/comments/25kuga/what_exactly_is_the_protocol_for_buying_a_car_on/chi83ck

I've been looking to buy on Craigslist since my budget is $3000. Preferably less. If any one has taken a look at the little guide I linked, are there any of your thoughts to add?

I'm still worried about how to find a mechanic to check the car and how to handle the money. I've also seen these cautionary advices to make sure the seller signs the pink slips(?) correctly or it won't be properly transferred to me. So I'm still looking up the process to make sure the car is under my ownership. I'm living under my single mom and she doesn't exactly know how to help me. I learned she doesn't really negotiate with the dealership (which I heard is really, really bad) and I can't afford paying the ridiculous insurance amount to share with her 2012 car. I'm looking at some Toyotas and maybe Hondas from 1990's which I'm hoping I can get a reliable one. Or maybe an early 2000 if insurance can shoot me a much better quote.

Read more: Any tips for buying used car for a first timer?