I agree with Machka - head to a large parking lot on a Sunday morning when it will be empty. Ride figure 8s and then ride figure 8s one handed. I have found that holding the bars somewhat loosely seems to smooth out the track. Riding one handed is helpful in signaling turns so it is useful to practice. Same with reaching and replacing water bottles. As for looking behind, so what's wrong with a mirror? Whatever you are uncomfortable doing, practice that at a time and place where there is no pressure.