Hey there Sean,
When it comes to your vehicle theres a few things to know.
Towing capacity, as listed in your owners manual or on rare occasion on the drivers door frame is the total weight the vehicle can tow behind it. That includes the load, trailer, and extra cargo within.
So in my case, 01 Pontiac Montana, the towing capacity of the van is 3,800lbs.
The next thing you want to figure out is the weight capability of the trailer receiver, or hitch. Stamped on the body you should find the maximum toungue weight and the capacity of that hitch, more often then not, it will be referred to as a "Class" Heres a good guide. http://hitches4less.com/trailer-hitch-classes.html
Tounge wieght is reffered to the amount of force that is pushing down on the hitch itself. This can be adjusted to a degree by loading and purchasing a proper bar that makes the tailer level. The more level the trailer is, the better the load is held by the wheels, instead of forcing down on the hitch, or pulling up.
The least maximum capacity should be what you go by. If you have a 3000 pound capacity on the vehicle, but a 4000lb hitch, do not exceed 3000lbs and the same in reverse.
Next is the ball. On the top of the ball will be stamped with the ball's size and capacity. Again like above, don't exceed the minimum weight capacity.
Check the hitch on the trailer to ensure your ball is of the correct size. Too big it wont fit in, too small and it will pop out. Even if it looks like it fits, do not risk it.
The next thing your going to want to watch for is the Bar's rise and drop. If you pin up to your trailer and it looks like the back of the trailer isn't level you will need a bar with a rise to level the trailer (common issue with some cars and minivans), likewise if the trailer looks like its nose down on the vehicle, you may want a hitch with a drop to level it out, (Common with 4x4 pickups). The more level you can make the trailer, the better. The trailers axles will bear more weight then the receiver ever will.
Chains are a commonly over looked item. Ensure the working strength of your chains is at least the same capacity of the trailer or better and long enough that the vehicle can turn fully without binding the chains. Cross your chains underneath. Also ensure the chains aren't too long and rub on the pavement. The idea here is that if your trailer pops off the front of the hitch should not strike the ground.
Also if your towed load exceeds 1000lbs, consider getting a trailer brake controller. It will prevent any unwanted jackknifing.
Happy towing!
