I put it on my lap, just like the old non-moving paper maps. What you don't want to do is to look at it constantly. You find a heading that will work and then you hold that heading (or the autopilot does).
You need some kind of cover, I have one in leather that folds open like a book. About 15-20€ will get you a nice one. This will also give some protection against shocks and falls.
Depending on the sun angle, I put the Nexus7 on my left leg, my right leg, or on the RH seat if unoccupied. A cigar-lighter USB adapter provides plenty of power. If aircraft power would fail, I still have more tablet duration than fuel duration.
I do airways flightplanning on Rocketroute and then copy/paste the route data to Skydemon. I have wifi-only and in most hotels and airports you get access. I have 32GB version and that is plenty but I do a lot more on the tablet than just aviation.