For me, there are 3 basic ways, in increasing difficulty:
1. I make a lot of bowls with the same basic form and allow a certain
influence by the wood itself.
2. I make sketches with idea or concept as a starting point, search
for the best fitting wood and if its a "dry wood" project, I make an
exact drawing, often using just plain maple. With wet woods, there is
no use in exact drawings, because because it will chance its shape,
such as holly.
3. With the wood in charge, I just follow its directions, using the
most whimsical wood I can find such as crotches and burls, which are
seldom without holes, bark inclusions, nails, stones or rotten spots.
As always, don't mind my english.

Dutchturner Chris