Look in the yellow pages or Internet for auto service in your area, phone and ask cost for an inspection on a vehicle you are considering for purchase and make an appointment.
Without going into further details just do it when you find a car of interest, or send me a link and I will check for red flags.
Most good mechanics will have a pretty good idea of what to look for when inspecting a car. One way to make sure the mechanic is quality is ask to have a ASE Master mechanic inspect your car. This will cost a bit more (probably a bit over $100), but you'll know he's doing a good job. Just call up shops to see if they have an ASE master mechanic on staff and ask when he can inspect your car.
One way to get a bit more out of the inspection is to bring a form for them to fill out during the inspection. One good one can be found at OnPointInspection.com. This will help you make sure that all the important points are checked in the inspection.