The best thing I did when I first started out was take the RV to a empty parking lot, set up a few markers and try to miss them while parking, turning and in general backing up. Since then the second best thing I still do, when in doubt, is get out and look.
Hand held radios are pretty handy in just about any maneuvering task. I still see the DW outside waving her hands around and shouting directions while the driver not only can't hear her but can't see her either. Generally in these circumstances an argument between them is inevitable.
The radios have removed countless frustrating experiences for us.