What's your budget, exactly? The OP only mentions that the ones you're looking at are in the $16k range, which I've got to say is an INSANE amount of money to spend on a used car. Also an insane amount to spend on your first car.
Look at vehicles in the 120k-150k mile range. You can find loads of early '00s car for about $5k with that mileage. Throw another ~$1k at it for maintenance/repair and you can drive it for another 90k miles, easily.
DO. YOUR. RESEARCH. I can't stress this enough. Every car model, brand, and even year ranges have their own little quirks. Sometimes it's just minor annoyances that you can tolerate, other times you may find that the car you picked is a steaming pantload with wheels on.
Things to check:
-get the VIN and run it through carfax or some similar service. Look to see if the car was ever abandoned, salvaged, repainted, stolen, etc. Also look at how many owners the car has had - fewer is usually better.
-tires. New tires are expensive. Not a deal breaker, just saying. If you see bald patches or bits of wire sticking out, don't discount the car. Just get the tires replaced as your first step. Assuming nothing else is wrong with it.
-front end alignment. Easy to check, just go to a straight road that doesn't have any traffic. Take your hands off the wheel while going veeeeery slowly and see if the car lists or pulls to the left or right. This can be cheap or expensive depending on what the cause is...could be it just needs to be calibrated, could mean the owner rode up on a curb at speed, ruining the front suspension.
-fluid levels and leaks. Check oil and radiator fluid for proper levels. Oil may be black or dark, but if it's quite low then be leery. If the owner doesn't know when the oil was last changed, move on. Power steering and brake fluid should be checked in a shop. Brakes *may* feel weak if the fluid is fouled. If the steering wheel vibrates or makes a whining noise when it's fully turned at a full stop, it may need fluid. If the car is leaking any fluids, don't even test drive it.
-brakes. Squishy/weak brakes can be either fluid or pads and shoes. Pads and shoes are pretty cheap, also the most likely culprit.
-stinky interior. Moldy smell might mean the car was abandoned or had a window that was stuck open. Or that it spent some time at the bottom of a lake. Could also mean that it needs a new cabin air filter. Check the carfax to find out.
-windows/interior/etc. Make sure all windows roll up and down. A broken electric window is a massive pain to repair. Make sure you can adjust the seat. Test the climate control, heat should be hot and AC should be cold.
-driving test. Take it out on the road. I'm assuming it'll be an automatic transmission, so make sure that the car feels smooth when you're accelerating - no hitches or jerking when it shifts gears. Take it on city streets and also drive it on the highway.
-idle test. Drive the car until it gets to operating temperature. Park the car and leave it running. Make sure that it idles smoothly and doesn't stall. Make sure that the idle stays steady when you turn on the AC to full blast and have the radio turned up, both at the same time. Check the temperature gauge while parked...temperature should slowly increase and then a fan will engage that will level the temperature or at least slow its rise.
That's about all I can think of.