Many folks ask if they should buy new or used - buy used and put your money in your pocket for other things. New cars smell nice but can run you $30 to $60k versus a nice 5-10 year old with under 100k miles for around $10k or less. These cars are "AS IS" and you will want to get them up to snuff but it's still cheaper than buying new and having that debt hanging over your head and monthly payment you can't afford. Now is not the time to have huge obligations!
So you decided to buy used and noticed some things - get to a trusted mechanic and say the following "I want to fix what is dangerous plus a list of what I should do down the road. Red light means do now, yellow means soon, green means when my ship comes in." A good mechanic will do just that. Fix the red light things and throw in a couple of simple things with big effects i.e. have the oil changed at a place like Jiffy Lube or Kwik Kar as they will check and fill all your fluids. Have the tires rotated and balanced so you don't shake going down the highway. Get an alignment if the car pulls to one side - not a good thing. If they want you to fix the brakes and rotors need re-doing, have at it - you want the car to stop and go.
My other favorite service to keep you going is a transmission service - either flush and fill or pan drop with new filter, etc. DONT DO THIS IF OVER 100K MILES. If you can keep your brakes your engine, your transmission, your radiator, and maybe your power steering systems clean that preventative maintenance can save you money down the road. Replace your wiper blades while you are at it so you can see. Does not hurt to wipe your windows inside and out. My favorite product for exterior windows is Rain-X 2 in 1 - cleans and repels water. You can use Windex on the inside if you want. Blue Magic makes a good headlight cleaner - just buff it one, wipe off with some Windex and you can see further at night.
Nothing says "new to you" like cleanliness. If you have $100 take it to a place like Aqua Car Wash and get an inside and out detailing job - they'll clean the upholstery, the carpet, the mats, and wipe everything down - worth every penney. If not, get a vacuum, some wash and wax, and wash down the insides and outsides. For spots on rug, Blue Magic makes a good product called Spot Lifter, they also have a carpet and upholstery cleaner and some good value leather cleaners and conditioners. That keeps your leather from cracking. Scrub those tires and wheels and after dry spray the tires with some Blue Magic or Black Magic Tire Wet - really looks great.
Throw in a complete fuel system cleaner in the gas tank while your at it to help it run smoother and save gas. Gumout Regane is good at Wal-Mart, etc.
So you bought used, fixed the broken things, the car drives straight and is clean inside and out.
Now take that extra cash and pay your insurance!