First aid for the car itself:
Get an hydraulic jack, like these, that are really cheap at places like Walmart, and toss the piece of crap jack that came with the car. If you ever change a tire, you will be so glad to have it.
Also, scroll down this page, until you see the tire plug kit that costs $7.99. If you ever pick up a nail, you can plug the hole with this, and then reinflate the tire with the inflator below that costs about $17, and plugs into your cigarette lighter. It costs about $30 to have a shop repair a tire for you, and doing it yourself takes only about 20 minutes. If you ever know you have a leak, but can’t find it (sometime you get a puncture, but the nail pops out) spray Windex on the tread, and look for bubbles.
Also, RE: the inflator, you can ruin a tire by driving even a block with it flat, and sometimes they lose air if you bump a curb hard. Most gas stations charge 50 cents to use their air hose. It adds up, and it’s so nice to be able to inflate the tire in your own driveway.
While you are in the car section, look for the lug wrench with the pipe extension, because the wrench that the car comes with will be about eight inches long, and it’s really hard to get enough leverage to get the nuts off with those. Also, by a pack of assorted spare fuses for your car. You probably won’t need them on a new car, but it can be so annoying when something won’t work for lack of a 10 cent part.
If you are going to be a commuter, or go on road trips, think about ditching the doughnut spare. You can put only 50 miles on them, and are not supposed to go faster than 50mph with them on the car. If you go to a junkyard, you can get a rim (wheel) for the car, and then get a used tire either from the junkyard, or from a tire store. Explain you want it for a spare, and they won’t give you much trouble over selling a used tire. A lot of people buy 50,000 miles tires, and replace them at 40,000 (commuters especially), so you can get a pretty good tire for spare.
I worked in a shop for a while, so I have changed a lot of tires, and I really know about this.
Also, never use Fix-a-flat. It usually doesn’t work, and is a pain to get out of the tire; so much so, that many shops have an extra charge for repairing tires that have Fix-a-flat in them.