How to buy a used F-150

Most of the points in this article can be applied to the purchase of any used vehicle, but we are going to focus on Ford trucks in particular.

Damage - Be sure to be aware of any damage to the vehicle and get estimates on how much it will cost to fix. That way you can negotiate a better deal based on the extra work that needs to be done.
Mileage - Is it really high mileage? If so, was it highway mileage? Has the odometer been tampered with?
Engine - Do you need all the power of the 5.4L V8 for towing, or can you make do with the more fuel-efficient 4.2L V6? Is the engine too noisy? Does it make any strange rattling noises? Is there any hesitation?
Condition - Look for rust in critical areas such as the frame. Are there any squeaks or rattles? Does the transmission work properly (no hard gear changes)? Does the truck puff smoke when it starts? Does it burn oil? Overall does the truck look like it's been taken care of? If not, you might be better off to keep looking.
History - Was the vehicle owned by just one person prior to you? Did the previous owner abuse the truck? Did they lease it or buy it? Are there any receipts for previous work? Do you know if there were major repairs done? Was the truck in an accident? Was it a write-off? A great way to learn about the history is to run a CARFAX check on the vehicle.
Features - Does it have all the features you need? Power windows, locks, etc. can be expensive to add on later if you want them.

Insurance Cost - Does it cost more to insure a Lariat than an XL? Check out insurance rates in your area to be sure you're not paying too much, or more than you can afford.
Price - Is it a reasonable price? Check Kelley Blue Book online and see! Dealers tend to have higher prices than private sellers, because of the overhead of the dealer, salesperson, etc. Also, buy what you can afford. There's no sense putting out a second mortgage on the house just because you want the bigger engine.
Warranty - Is there a warranty with the vehicle? If so, what is covered? What isn't?
Recalls - Be aware of any safety recalls that might exist for the truck. Check recalls here.

I would highly recommend getting a qualified mechanic to inspect any F150 you're thinking of buying. And remember, buyer beware!