Go to your local yacht club. Not the one where people are in sport blazers, the one where there is always someone in the back of the lot, fixing a boat. Post your name and address on the bullitin board saying you are interested in crewing and learning. You'll get a call.
Go from there. Start small - you learn the feel of the boat first. Then go from there. I started out in dingys - spent several summers crewing on bigger boats including Sweden 34's J-35's.
Respect Mother Nature- always.
I also recommend you do some reading. Joshua Slocum - around the world alone, and Sir Francis Chichester's Books.
