Please recognize that opinions on this subject are rampant. Not everyone agrees. I strongly suggest you spend enough time sailing to learn what is truly important to you before buying your own boat. Racing is the fastest and easiest way (in my opinion <grin>) to gain experience, but it usually isn't very hard to find cruisers to sail with either.
Just as an example, many people (a great number of whom don't single-hand) will tell you to rig lines back to the cockpit. I sail single-handed more often than not and I strongly differ. On my 40' center cockpit, all main sail halyards and reefing gear and spinnaker halyards are at the mast. I really like it that way. I would not begin to suggest that my solution is right for everyone, but I do think you should develop enough experience to come to your own conclusion.
That said, here are my thoughts based on 30 years of sailing, both cruising and racing. I sail a LOT, mostly single-handed, sometimes with a friend, and once in a while with a bigger crew.
1. Sleeping is important. Be sure your berth is comfortable. I include in this area being able to make the bed easily (if that is important to you). This led me to a center cockpit boat with a center island queen aft.
2. Cooking is important. This led me to a boat with a large galley, near-centerline sink, and relatively large amount of counter space.
3. Sailing is important. This led me to a conventional main with full battens, relatively narrow beam, lots of sail control, adjustable backstay, and space for a big sail locker.
4. Entertainment is important. I have a stereo with iPod input, good Internet connectivity, and a couple of TVs.
5. Ground tackle is critical. Get (opinion) a new generation anchor (Rocna, Spade, Raya) and solid ground tackle (HT chain and appropriate windlass).
6. You can't have too much electrical capacity. Fit as many batteries as you can. Make your charging arrangements based on your planned sailing grounds: options include more than one of shore power, generator, solar, and wind.
7. Sanitation is a big deal. Consider a Raritan Electroscan -- learn more than you care to about the associated issues.
8. Laundry is a major issue. Have a plan. Washing in salt water should NOT be part of that plan. It takes more fresh water to rinse the salt out than you save by using salt water in the first place.
9. The patterns you have developed living ashore are likely to be exhibited living afloat. Accommodate. You have to find ways to live with yourself and be happy.
10. Get rid of stuff. Go for a drive or a walk or have a chat with friends. Figure out what stuff is really important to you and get rid of everything else. I spent something like $15k storing stuff I ultimately sold for $3k. <sigh> Learn from my mistake.
11. Find community. Even if you are a loner it is good to know and stay in touch with the liveaboard/cruising community. Information is power, and these folks (the community, not necessarily Sailnet) have it and mostly are willing to share it. You'll get information about moorings, anchorages, water, fuel, transportation, services, and other very important things.
12. Maintain your standards. Living aboard doesn't have to be camping. Develop a lifestyle that makes you comfortable with who you are and how you live.
If you get to the Annapolis area you are welcome to come sailing with my girlfriend and me. I have lots of facts and opinions to share and I think I'm pretty good at labeling them accordingly. <grin>
sail fast, dave
S/V Auspicious
lying City Dock, Annapolis, MD