Don't promote your book by tearing down the entire rest of the field. The gentleman who talked of his book being different from the entire rest of the fantasy field, which is composed of quest tales of young white orphan boys and their swords--not only has he not done his research, he's just gone and offended half the room at World Fantasy, because some of them write and like that stuff, and some of them have been writing and publishing completely different kinds of fantasy for ages now and don't like being told they don't exist.
Do plan ahead. Saying to a friend, "Are you free for lunch tomorrow?" or "How about dinner Friday? Where shall we meet?" may be the difference between seeing them for a happy few hours and never finding them again. Knowing that I would definitely get to see dear friends I hadn't seen in a long time was a steadying point and a high point.
Don't make those plans vague. "Oh yes, I'll see you later! And meet your fiancee!" Um. Not so functional, that. Sorry!
Do leave space in your bag for books. Wheeee!
Don't buy a membership to a con that has a capped membership and a waiting list if you have publicly expressed scorn and loathing for its subject matter. Tacky, tacky, tacky. Seriously, people, how hard is this? I don't really like horror. I don't go to World Horror. There! Done! How hard was that? I do not trip and fall and find myself on the membership list. Similarly, if you don't like fantasy...and you have been very clear that you don't like fantasy...and the convention is World Fantasy...well, you do the math.
Do try crazy nearby restaurants. The top of Neiman Marcus was surprisingly not overpriced, and brought us lovely things; the weird iPad-themed restaurant worked well and was easy for a group that was not paying all together without actually being fast food. (But Boudin Bakery is also still good.)
Don't go to an event at the Town and Country. Seriously. It sucked, lo, mightily. I didn't even have the worst issues with it, of all the people I know. But even minor things like the Which Towel Type Won't We Get Today? game were annoying, and the disability issues were far, far worse. This is everyone's problem.
Do tell writers you meet if you like their work. Even if it's little things. They will appreciate it. In some cases it may get them through tough weeks.
Don't grab somebody by the thigh as she is walking to get her attention. I...feel like all the qualifications on this one are a bit moot. Other people's thighs: they are not yours. When you're male and they're female; when you're an editor and they're a writer; when you just met the previous day and are not old friends; when they have a balance disorder that affects their mobility--all these things are additional problems. But in their absence it's still not okay to just--in person I tend to go into rant voice on this. Because we do not! We just don't! We don't grab other people by the thigh! What the hell! Other people's children!
(I also feel obliged to say that it is not an editor I have worked with or would work with. The folks from Shimmer, Fantasy, and Tor.com were all great.)
Here's the thing. I was watching hockey last night, and one of the Red Wings came crashing into the Wild net, straight into Josh Harding. And the announcer was saying something about how he was not sure that this person intended to interfere with the goaltender. And I watched the replay and said, "No, but he sure didn't intend not to." And that's the standard. It is his job to attempt to steer clear of mowing down the goalie. And that's kind of how I feel about this. Did the person in question mean to sexually harass me? Probably not. But he sure as hell didn't put in even rudimentary kindergarten level effort to respect my personal space, either, and that's quite enough. It was not incumbent on the ref to ascertain that the Red Wings player had great evil and malice aforethought; it was enough that he did not make an effort to avoid the thing that was over a line. And this? This was over a line.
Nor was it the only such incident I experienced at this con. It's just the one I can describe most clearly at the moment: I was walking out of my reading, and this guy grabbed me by the thigh as I was walking past, to tell me that he liked my story. And the stuff I said above, about saying nice things to the writers you like? It goes out the window when you invade their personal space first. Truly.