just research what to look for in an old boat.. like read don caseys this old boat ?
That's a good place to start, BEFORE you start seriously boat shopping. Buy Casey's book and read it. Especially the first three chapters or so. Re-read those chapters. Carry the book with you everywhere, even as you're walking down docks looking and dreaming. You'll learn how to kick tires with a critical eye- with the book in hand, when you see something that catches your eye, you'll have a quick reference.
The book is also a prop. liveaboarders and marina rats are by nature curious, and some are borderline paranoid. They see a young guy amilessly roaming the docks, they see trouble. They see a young guy roaming the docks with a Casey book in his hand, that's different. That's a future member of the club. It may mean that somebody invites you to check out their boat, gives you tips you wouldn't have gotten otherwise, and might even turn you onto a boat for sale you hadn't heard about.
A piece of advice given to me when I started boat shopping years ago is to look at at least 5 boats you KNOW you DON'T want before you start getting serious. Too small, too big, too much draft, too expensive, ugly, whatever, but make sure they are boats that don't appeal to you at all...not even a little. That way, you get your inspection skills sharpened without running the risk of falling in love with the first boat you see.