I've been to several. They're pretty good about posting the schedule a couple of weeks out so my suggestion is to print it out and mark which items are 'must-do'. There will always be conflicts so don't set your heart on anything.
Lines for panels are long but really quite well organized. They *don't* clear rooms between panels so you may be well-advised to camp out if there's something you simply cannot miss.
The showroom floor is *packed* but interesting, both for the people-watching and the items available. Lots of booths have con exclusives and give-aways at various times. Many also have autograph sessions, too. Don't expect the boothies to be terribly well informed about schedules-look for a schedule posted or keep asking until you find somebody who seems to be in charge. It's the difference between day-workers and company employees.
Hall H (I think) is a huge room where many of the screenings for upcoming shows and movies are, as well as the most popular panels with celebrities. Expect huge, hours-long lines. Mostly I don't bother but once you're in, you don't have to leave since there are restrooms right in the hall.
Food is available but pretty bland and quite expensive. Many (most) of the panel rooms have water stations so you can re-fill a bottle with water if you've brought one. Carry some cereal or energy bars with you.
Wear comfortable shoes. Expect to be jostled and stepped on but most attendees are looking to have fun, just as you are.
There's a small publication put out daily with schedule changes and lists of autograph sessions. Some are ticketed or lotteried, most aren't. Look for stands holding them outside of the show floor and near escalators.
Take the time to familiarize yourself with the traffic patterns. In the panel areas, halls are designated as to in or out. It seems like extra walking but it really works much better than non-directional where gridlock used to happen regularly when panels let out or started.
Have a good time!!
Jan