Because I'm blocked on fic, afraid to look at my flist after so long, and avoiding homework:
1. Never Leave the Baby Alone
This especially applies for if you actually took your baby to the con. In related news, if you are an older-type person and taking a child or infant (or pre-teen sibling) to the con with you, it is your responsibility to make sure that that child/infant/pre-teen is not exposed to the sort of stuff that you don't want them exposed to.
Most cons are pretty good places for kids, but that doesn't mean that there won't be someone making inappropriate jokes, selling porn, or groping people. Keep an eye out. Check and see if the con is kid-friendly before you go. Don't expect there to be childcare or inexpensive food anywhere in the area.
For kids, I would suggest cons like Connecticon, Anime Boston, and Otakon (although the bigger the con the more likely it will be for you to lose them). New York Comicon (the one time I went) was way too crowded for anything that can be lost of smothered. Cons like Arisa (a fantasy/si-fi convention in Boston) are very kid friendly but generally have an older crowd and some adult-themed panels.
If your kid is uninterested in the sort of con you're going to, please do them a favor don't force them to come with you. Likewise if your kid is the sort who would make other con-goers miserable (read: obnoxious). Do everyone a favor and leave them at home with a babysitter who will also not leave them alone.
2. Pack Light
There are a lot of things that you might want to bring to a con: hairspray, duct tape, deodorant, snacks, something that will play Caramelldansen on loop for the entire convention. That said, if you've got a great big bag full of shit you're going to have a hard time once you get tired and your feet start hurting and you can't find your wallet. Having a big bag will also get in the way of all the awesome pictures people will want to take of your awesome costume.
On the other hand, the things I listed above (minus the caramelldansen) can be really handy during the con. In this case, you should have a meeting with your friends to split the supplies between all of you or elect someone to be the shirpa for the day (preferably someone who isn't in costume) and give them foot massages in compensation. In general, the con is better when your hands aren't full.
One good idea is to work a bag or purse into your costume. I have, on occasion, made a prop which can also serve to carry the most important things. I try to keep it light though: a wallet full of money/credit (see #3), ID, phone, and glucose meter.
3. Come Well-Funded
Remember girls and (unlikely) boys: cons are expensive. Even if you aren't paying to stay in the hotel, you're probably going to shell out quite a bit of cash for other stuff. Before going to the con, work out a budget for how much you can spend on food, travel, and buying awesome stuff.
I would suggest that you withdraw a certain sum of hard-cash to spend only at the dealers room and (ESPECIALLY! DOO IT!) the artists alley, since not all dealers will take a card and it will help you keep track of how much you're spending.
If you want to save money at the con by not eating, please DON'T DO IT and skip over to #4. One option is to pack some sandwiches and juice boxes and only eat those. Personally, this doesn't work for me since I find the food court/restaurant/whatever to be a nice respite from the business of the con and I tend to buy food even when I do pack sandwiches.
4. Don't Be a Bitch
There are numerous ways to prevent being an asshole at a con. Remember that everyone is there to have fun and be weird. Nobody wants to deal with an asshole, especially not at a fun event. Here are some ways that you can prevent being a total bitch:
a. Eat and stay hydrated
Take it from 17 years of diabetes experience, fluctuations in bloodsugar will seriously impact your mood. The atmosphere of the con is exactly the sort of thing that results in your bloodsugar getting fucked up. So eat. Eat at every meal. Eat a balance of carbs (complex carbs like oatmeal, whole wheat bread, and potatoes are better) and protein (peanut butter, cheese, meats, etc). Try to avoid obscene amounts of sugar and caffeine. If you do consume these things, make sure that you accompany them with some protein and hydration. Anyone who would like a detailed description of how these thing affect your bloodsugar (and your mood) should go ahead and ask me in a comment.
Likewise, staying hydrated is really important to maintaining your mood (as well as your general well-being) at the con. A water-bottle is one of those things that you should consider bringing with you. If you don't, make sure to make regular stops at a water fountain.
One of my best secrets for rejuvenating myself from what I call "con burn-out", (when I get really tired, pissy, and angry) is as follows: I drink enough water that I start feeling a little ill, wait a while, pee, and then I do jumping jacks or cartwheels. Totally not kidding. The combination of hydration and exercise makes me feel awesome again every time.
b. Get enough sleep
It's hard to get enough sleep at a con, but the amount of enjoyment you'll get from not being a total asshole will be worth it. You know best how much sleep you need, but I would suggest at least 6 to 8 hours every night. Instead of overloading yourself on caffeine and sugar (as I mentioned above), try taking naps in the halls or an empty room throughout the day (with a friend guarding you, of course)
c. Don't get overstimulated
Take some time, every day at the con, to relax a little. Rest, read a manga, go eat a meal, go sit in a viewing room for a while. Too much stuff over the course of the day can make you feel overstimulated and overwhelmed. Being overwhelmed can turn you into a bitch. In order to be more whelmed (as Robin might say) make sure that you find some time to unwind.
e. Just be fucking nice to people
Yeah, so basically the point of that is that even if you're having the worst con of your entire life, even if con-drama (see #6) is driving you insane, you have not right to be an asshole to people. Everyone has a better time when everyone is having a better time. Fake it til you make it.
5. Take your meds
If you have ADHD/OCD/diabetes/chronic foot pain/whatever, make sure that you take your meds and have whatever it is you need to manage your illness/disability while you're at the con. Strange places can be shitty if you have a chronic illnesses. Make sure you have everything you need to keep yourself healthy.
6. Avoid con-drama
Con-drama is an essential part of any convention. Sometimes it happens to other people and you get to watch the girls gathered in the bathroom talking about how "ohmigod and he broke her cosplay". That's pretty fun. But sometimes the con drama happens to you, and when that happens it's important to remember that the con should be somewhere fun and that drama should be saved for once you're safely back at home.
Good ways to avoid con-drama are to not be a total bitch (see number 4), don't spend time with people you don't like, and take time away from people when you're starting to feel like an asshole.
One of the best ways to do all of this is to plan your cosplay so that you're in a group with people that you won't mind hanging out with. If someone you hate signs up for your cosplay group, if you're being hounded to do a couples cosplay with someone you're not into (suggesting a ship cosplay is one way that nerds hit on each other. Not always, but sometimes), casually back out of the agreement. Avoid the people you don't like and save yourself the drama.
7. Hang out in a small groups
A good way to avoid con-drama, getting overstimulated, and being a huge bitch is to keep the group of people you're hanging out with at the con as small as possible. I'm not saying that it can't be fun to hang out in a horde, but I always prefer to spend the majority of my time with two or three people and then hang out with my other friends just a little bit over the course of the con. This means that you don't have to keep track of people or worry when lose anyone, and that you don't have to miss anything you really want to do, which is the next point.
8. Do the stuff you want to do
There's a lot of stuff to do at a con, so you should schedule your time wisely. I suggest bringing a highlighter or pen to the con with you and then circling/lighting all the events that you really want to go to. Make sure to mark the things that you ABSOLUTELY CANNOT MISS OMFG because I guarantee that you will not be able to get to all of the shit you want to do, especially when there's multiple events going on at once. In addition, make sure you leave time for eating, dealer's room, and waiting in line.
At cons like Anime Boston and Otakon, you should be waiting in line for at least 30 minutes to an hour before the beginning of your event. If it's a particularly cool event I would suggest setting up camp in the hallway a little earlier.
For smaller cons the lines might be smaller, or non-existent. But there will always be a line for the masquerade well in advance, and you should plan accordingly.
9. Be polite when asking for pictures
One of the best parts of conventions is the crazy outfits: the cosplay, the goths, the steampunk folks. You'll probably want to take pictures of these people. You should remember that there is an etiquette for taking pictures and the etiquette is ask first, don't be mean. You should ALWAYS ask before snapping a photo of someone, even if they're wearing a giant gundam costume. Ask verbally. If they say no or keep walking then don't push it.
The few exception to this rule is if there is already a large group of people already shooting photos. If that's the case, go ahead and join in. Just make sure that you aren't the one keeping them from going about their day. Likewise, if you're trying to get group or candid shots it not really necessary that you should ask. If someone sees you taking a candid (or if you're a nice person) casually go over and explain to them that you were trying to capture the moment and ask if they'll let you keep the image.
Finally, it's perfectly okay to ask people in a ship costume to do something shippy (hug, kiss, "yaoi", whatever) for you, but make sure to ask only once and to not be a creeper about it. Plenty of people are perfectly okay with making out for the camera, but if they aren't there's no need to make them uncomfortable.
10. Don't be a sleaze
Conventions are a great way for geeky people to meet other geeky people of the opposite or same or undefined gender for sexytimes and/or a relationship. Oh do I ever know. But it's important to know that the rules of real-life (ie don't be a dick) apply to us geeks at the convention as well. It's fine to hit on/be hit on, but remember that when someone isn't into you then it's time to back off.
Just because someone is in a provocative costume or dressed as a character that you ship with yours, it doesn't mean that they will appreciate you hitting on them or even commenting on the sluttyness/shippyness of their cosplay. People who are crossplaying are not guaranteed to be gay, so keep that in mind when hitting on them.
Never ask anyone at a convention for anything inappropriate (like a massage, that's right creepers I'm looking at you), don't touch/glomp/grope/hug without permission.
Anyone with questions about how to hit on/get hit on at a convention (or anyone who wants to hear my awesome stories) should comment below.
THE END! YAY! Read my advice to cosplayers here