If you've come to the forum already, you are 1/2 way to getting it right. There is some excellent info. in stickies in the towing forum. If you are meaning the weight distributing hitch, the best thing you can do is learn how to do it yourself and it's not all that difficult. Above all, do not let a dealer do it or advise you.
Chances are, even if an "expert" sets it up, you may need to tweak the amount of weight being transferred to the steer axle on your tow vehicle by adjusting bar angle or number of chain links (from loading the TV and TT with more or less weight than usual).
Some take more effort to install and set up like the Reese dual cam WDH. You have the option of getting a basic WDH without sway control and adding friction sway bars or getting something with integral sway control (Blue Ox, Equal-i-zer, etc.). In most cases, you'll want sway control.
In addition to the WDH, there are other considerations like the brake controller, appropriate tire pressure, payload ratings, etc.
Info on your trailer and tow vehicle would help.