So this is the first time I am looking at buying a used car, lock stock and barrel, cash up front.

Problem is, other than using Carfax, Kelly Blue book, and a few other sources (including dad) I'm not sure what I should be looking out and watching for.

Any advice?

First off, millage. Also, get a good test drive first to see if you notice any weird running.Finally, dont get lock into anything. Upon purchase take it to your own mechanic for a check. If he finds something wrong. Get your money back. Just remember the buyers remorse law.

I just bought a used car last year. I was looking for mileage, fuel efficiency and dependability. There's a number of great sites which rank used cars, but my favourite was searching for customer reviews. I learned a lot about the cars I was considering - and stuff they don't mention in the usual commentaries. Also make sure the dealer is a good one and verifies that the car has never been involved in a serious accident.

After I'd narrowed down my choices, I spent a fair deal of time comparing prices. I eventually ended up with a 2004 Nissan Sentra, 55,000km, for $9500 (Canadian). I was very happy with my choice and I still am.

Check everything. Oil, tire pressure, history reports (if there are any), look under the car, check for rust (especially in rural areas or places that rain or snow a lot)... Take it for a test drive. Test it out on short tracks and take it for a spin on the freeway. Ask if you and the salesman (the dude selling you the car) can take it to a local mechanic and check it out together. Ask when the last maitenance was on it. Do a full inspection of the interior and make sure all the gauges work properly. There is nothing more embarassing than having a 'check engine' light come on randomly after purchasing it.

Make sure that you get the title as you purchase it. If they don't have the title, then there might be something wrong with the car. You can draw up a new car title at your local courthouse, but its always good to make sure you're getting the original.

Check the interior for stains and the like, good rule thumb is that if the interior isn't that well taken care of the rest of the car is not either.

Most of the good advice has already been stated.

The only other thing I can think of is, if you can find one being sold by a little older lady, take it. Of course, this isn't an always thing. But when I was in the market for a car and stopped by a few being sold by owner, the ones owned by more elderly folk were in much better condition and usually were for a much more reasonable price.

Pretty much what everyone else said.

Get it checked by a mechanic you trust before you buy. If the seller won't let you, then that's a good sign you don't want that car.
Also, if the seller doesn't have the title, I'd say "no sale" right off the bat. If they don't have it, it's a sign that either they're not bothered enough about the car to even keep track of the title, or something's up with that car (stolen, totaled, whatever).
Take a look at the title too, and make sure it doesn't say anything that raises an eyebrow, like salvaged or flood damage or whatever.

One of the most important things to look at in my opinion is the actual person selling the car. What kind of person are they? It'll often give you clues about how well the car was taken care of, and how they drove it. You don't want to buy a secondhand car that's been driven by a teenager.

Consumer Reports is a good place to look up reviews on used cars. They send me a whole book every year on car buying - what's good, what's not so good, what holds its value best after a few years, what kind of mileage you'll really get (don't trust the window stickers!), safety ratings, what kinds of problems are most likely to pop up depending on the age of the vehicle, how comfortable the car is, etc.
It's a great place to check out almost anything you're looking to buy.

Another thing is to ask is if it's ever had refinishing of any sort done; eg, body filler, glaze putty, or just generally repainted top to bottom, and what the car's frame is - unibody or frame - as well as what the panels are made of. Believe me, it makes things a lot easier for you and for any mechanic/refinisher you ever have to take it to, plus if you ever do get into an accident you can get a rough estimate off the top of your head if you know what panels are made of what, eg, Aluminum, steel, plastic, the like, if any are damaged and need to be repaired/replaced. Also, for the love of god, do not modify that car yourself unless you truly know what you are doing! Take it to a liscenced refinisher that can do the job properly; reason I say this is because at the vocational school I'm taking collision repair/refinishing at, there is a Mustang I'm stuck working on right now and the rear spoiler the owner put on it himself was absolutely covered in rust around the joint because he didn't seal it or the holes in the trunk properly.

See if there are any features on the car that were put on before it was back on the market, check for any possible leaks if the salesperson/seller allows you to, and see if the gas cap can be connected to the car with a cord; this way, you never lose it. Probably a silly piece of advice, but my mom's lost more gas caps than I can count. >.>

Everything they said, with a few added bonuses.

If there is no histroy, repair or otherwise, dont buy the car. I dont care how many people tell me "but it might be an awesome deal" chances are if you dont have a repair or incident history for your car, there is a REASON you dont have one. Not usually a good one.

Second hand cars are a difficult thing to buy in america, im told you dont have an autotrader Its a simple click click click here to get a used car, one that is independantly checked!

Hmm you have the DMV there though, try noting down the drivers plates and checking to see if there is any previous histroy of criminal activity with the car. Heh we have a texting service here now :3 which is awesome.

Good luck!