To actually address a few key things:
You need to think of what type of Con you want to go to.
-The most basic breakdown is media v literary. These days, lit cons cross-over a good bit (multiple programming tracks that cater to wider fandom ranges than just author/artist, but in no way are the overscaled hype and usually zzz-fests of media cons, say DragonCon, ComicCon etc, which are too much BS for too little in return). In no small way lit cons have shrunk attendance-wise, but to me this makes the con, guests and fellow fans much more relaxed and accessible.
Con season is about to kick off in a major way, so memberships and accommodations need to be sorted soon for many of them.
Just to prep you for the worst-case....
Getting a membership. For a few Cons, usually larger regionals, membership is something that must be taken care of well in advance (some sell out, some cut off on-line, or mail-in requests date, some have multi-step processes to take care of things, almost all have rate bump dates etc). It may not be so easy to decide just a short time before the Con that you're going. A new trend that I support is some mid-size and up regionals are capping attendance numbers, so should you choose a lit/SF over a media con, you should do what you can to determine how far in advance you need to commit and in what ways; just hit their websites. Some of these will soon stop allowing membership transfers as well.
If you don't buy a badge within certain windows, you're likely to have to pay an increased rate or perhaps not be able to buy one at all til the next window for next year. Add on to this sorting out accommodations, which can be another nightmare as sorting room nights (members submit room requests through the con's hotel/accommodation liaison) and costs and however much of their space a hotel is opening up... well, can be hectic. That said, if you've a few acquaintances who'll attend, and if you frequent Con FB page and forums, then it's very likely you'll find a community of folks who are well-prepared to help you with membership and accommodation, if things are tight in those depts.
The above can be a pain though in all, more than manageable. If you have a few friends along, they're still one of the best ways to seriously kick up your energy level for whichever of your fandom(s) you hit. There's no acceptable surrogate for a good con weekend.