Having driven a semi for many years, and owned a couple of 5th wheels before I moved into my coach, the best advice I can give to you is keep the combination as staight as possible at all times. Many want to crank hard one way and then hard another, I have found, moving slowly, to make small adjustments. The less you hard crank, the less you have to correct. Granted, there are those conditions where you must hard crank to jack knife into a parking spot but once the trailer begins to turn, start coming back underneith her and keep your unit as staight as possible.
I have never been one to use the hand on the bottom of the steering wheel, I am also not one to look out the back window, when driving a truck, there was no back window. I strickly use the mirrors and revese steer (if you will) the direction I need to go. Its just something you learn and get better the more you do it.
If possible, practice all you can in an open area by setting out cones or something, pay close attention to how fast or how slow your unit reacts to turning. The shorter the trailer, the faster she will react, the longer, the slower she will react. Go slow, make small adjustments.