Getting into waves myself. Biggest things that helped so far were:
Practicing quick waterstarts, and if you can fall and keep the rig flying so you can water start straight away.
Get as fit as you can - you use heaps more energy - particularly if you spend most of a session swimming (and you will at some point).

As for the wavesailing technique:
I have learned to get out through the waves and over whitewater, feel reasonably comfortable ducking the rig sitting on the sail (tip of sail into wave) and going through the rinse cycle.
Can't comment on actually riding waves yet as I seem to spend most of the time riding amongst them

Awesome fun in any case.