You must size your tow vehicle to exceed the total weight you will be towing. New or used your tow vehicle must be set up for towing. The original window sticker will indicate if your choice was set up with a tow package at the factory. DO NOT EXCEED the towing capacity listed by the manufacturer!
Try to stay under the max tow weight.
Give up any dream of great gas/fuel mileage if you are going to tow. It will not happen. If you live in the north with extreme cold in winter think long and hard before you go diesel as that can be a hassle when the temps take a dive.
Shop with weight in mind when you look at Travel Trailers. I own a Trail Light TT by R-Vision. It is about the lightest quality built unit in it's class. The company quit the Travel Trailer business in Feb of 2014 so if you want one used is the only option. If you can find what you want in top condition on the used marked (lowest price from private sellers) that will save you thousands!!!
In the end quality and weight of the TT comes first then match the tow vehicle to the TT. Read consumers reports to find something that is reliable. I am a big Toyota fan....they are built to last.
Never believe the salesman at a dealership....do your own research. Members of this board will always be here to help but all to often they recommend what they drive which may not fit your lifestyle. All too often the desire is for an SUV and the poster recommends his pick-up truck as the only best option.
Good luck in your search for that "perfect TT"