Equalizer (weight distributing) hitch hookup:
Found this info in a newsgroup and it appears to be quite accurate if not detailed.
1) Park your unhitched tow vehicle on a level road, measure the height of the front bumper to road, and the height of the rear bumper to road
2) Hitch up your trailer and pick a chain link on the hitch adjustment arms, remeasure the two heights. You will likely find that both measurements have dropped due to the trailer hitch weight. The important thing is to measure how much they have dropped from the original measurements.
3) You are trying to get the front and back to drop the same amount (not necessarily end up at the same height). If you find the front doesn't drop as much as the back, then add more tension to the distribution arms. If you find the front drops farther than the back, the reduce the tension to the distribution arms.
4) Finally you will find a setting such that the front and the back of the tow vehicle drops nearly the same amount. This is the proper setting.
5) Now look at the angle of the weight distributing arms. They should be level. If not, then you will have to tilt the hitch ball assembly slightly (by taking it apart and adding or removing a bushing washer).
6) When all is said and done, check the level of the trailer. If the trailer isn't level, then the ball must be raised or lowered. Hopefully you purchased an adjustable height hitch.
7) Hook up your sway control, lighting umbilical, and safety chains and you're ready for the road.
8) Check those lights and trailer brake action to make sure that all is working as it should be before you drive out on the road.