The idea of joining a crew is a fascinating one that I would like to explore further. How can I find a boat that needs a crew member? I would be willing to sail to Europe or down south!
There are a number of free crew sites on which boats looking for crew and crew looking for boats can meet. Try to sound interesting and present yourself as honestly as you can, responding to boats that interest you.
When we are looking, I am drawn to interesting sounding people who have a better reason to go sailing than "I've a summer off from college..." or "My dream is to sail....". Art or philosophy students might be a bit more interesting to spend 15 days at sea with, rather than a student of business or the law. I always ask a prospect to tell me about themselves and those who's reply gives me a real insight into who they are, move way up the list. There are a lot of folks out there looking to go sailing on the web, so you have to make an impression; you obviously are not going to be hired for your experience, at least until you have some. Read all the ads you can, posted by people like yourself who have little or no experience before you put yours together. I will never even respond to mile counters (people who think the number of miles they have sailed is important), or someone who thinks they can cook at sea because they are a professional chef ashore. "I sailed on a lake a lot as a kid, but..." doesn't hold much water either IMO, if I'm looking for offshore crew.
On the other side of the coin, choose a boat carefully; you are putting your life in the hands of a complete stranger. When a match works, it can be a lifelong friendship; when it doesn't it can be pretty unpleasant for all.
If you are free to walk the docks, Newport, RI & Annapolis, Md are two places a lot of boats depart from. There are a couple of "cruiser's regattas" (check the ARC website, to name one) that sail south each fall; find out where they are staging from and go walk the docks.
If you have the will, you can find a boat and begin the adventure, good luck.