Comic-Con International starts in San Diego sixteen days from now. I used to post long lists of tips to enjoy/survive it but I got outclassed by Tom Spurgeon so I'll just send you to his list. Pay particular attention to #2, which is to do online research before you go, and to #21, which is to go see at least one of the panels I moderate.
They'll begin posting the programming schedule later this week and once it's up, take the time to really go over it and make notes on what you might want to see. It also don't hurt to look at the list of exhibitors and at the map of the grand hall and to notate some booths or areas you want to check out. Wandering about with no idea where you're going is a good way to not get a lot out of the experience.
I'll add one more tip to Tom's list: Don't complain about the crowds. As I get older, I find I have a lot less tolerance for folks who, for example, stray from air conditioning when it's 101° out and then bitch n' moan about how hot it is…like I can do something about that. Comic-Con is crowded and in many areas, very loud. If that's going to distress you, do a favor for yourself and anyone who'll have to listen to you whine about that, and don't go.
This especially applies to those of you who've attended a lot of these cons over the decades and seem to expect that one of these years, you'll walk in and find that we're all back at the El Cortez hotel, there are less than 3000 of us there and you can sit by the pool and talk comics with Jack Kirby. If that's what you're seeking in San Diego, there's another con that tries to get as close to that experience as is now humanly possible.
And one more thing in that vein: If crowds and noise bother you, stay the hell away from the videogaming section of the convention floor. The folks who run those exhibits deliberately try to clog the aisles and out-decibel everyone else.
The convention website is a great resource. So is The San Diego-Comic Con Unofficial Blog, though their panel expert there hasn't seemed to notice yet that there are about eight panels that I do every year in the same time slots in the same rooms. They do tend to be dismissive about panels that are about comic books or which lack hugely famous people on them…but there's still a lot of good info on that site.
Pace yourself. Accept that it's not humanly possible to get into everything you want to get into or to see everything you want to see. Do not neglect the basics of life like sleeping or eating or bathing. Especially bathing.
I'll probably think of other things between now and Preview Night. For now, just remember that there's a great time to be had there but you need to do a little advance work in order to find it. The convention won't entertain you but if you know how to use it, it's a terrific place to entertain yourself.