My suggestion would be to buy a
small boat right now. Larger than 12 but smaller than 20 feet. Learn to sail it. learn to
capsize it and right it again.
Learn how to take care of it and fix it.
Maintenance is a big part of
boating, and the amount of time and effort it takes frequently comes as a surprise to
new boat owners.
Concurrently, register as available
racing crew (railmeat) at as many yacht clubs and
marinas as you can get to.
When on other skipper's boats - keep your eyes open, mouth shut and do as you're told. If you have a question, wait until a calm time before asking, and when your question is answered - nod sagely and take it in, regardless of how intelligent or stupid the answer seems.
If there are other people in your
family, involve them as much as you can.
Enjoy yourself and don't take anything that isn't a
safety issue too seriously.
Good Luck !