As I understand it US citizens travel to other countries far less than Europeans for a multitude of reasons, one of them being that pretty much everywhere is so very far away. Since I've been traveling since I was somewhere around 5 or 6 pretty much all over the Northern Hemisphere. Over the past year and a half I've been traveling as an as-yet-unpublished writer and thus feel I have something to contribute.
Make a list and turn it into a template
Anyone planning to do this writing thing is going to end up traveling to a lot of cons. Packing is hard enough under the best of circumstances and inevitably you're going to end up missing something important. Having a packing list template that you keep updating makes it possible to have that happen as little as possible while also packing as little as possible. Which is to say: plan thoroughly then re-plan when, inevitably, your plan doesn't survive contact with the enemy.
I don't wear make-up in my daily life. When it's a choice of putting on make-up and sleeping for twenty minutes longer, I will always choose sleep. Ok, I will almost always choose sleep. During conventions is pretty much the only time when I exchange the latter for the former. I would recommend this for men as well as women but, for now at least, it is more socially acceptable for women to wear make-up than it is for men. The reason for this is that while at cons you're inevitably going to get photographed, repeatedly. Without make-up you're probably going to end up looking washed out, especially if your skin tone is caucasian or asian, but the problem still exists for darker skin tones. Along the same lines, you should plan on wearing colors other than black and white as most of the time backgrounds are going to be one of those. See pictures of Mary Robinette Kowal at the Hugos for a very visual reference.
Have business cards
Even if you're still unpublished, having business cards is an excellent idea. For one it's a fairly inexpensive way to impress most people. For the second, writing out your contact information in the middle of a conversation is awkward to say the least. Mine come courtesy of Moo.com which I'm ridiculously happy with but there are certainly other very good services that do good work as well.
Have your work with you
This seems like such a no-brainer, doesn't it? But so far I have never managed it. I'm a hopeless procrastinator which means that usually the last of my packing gets done very late the night before I leave for any given trip. Which is why I would also recommend getting there a day early if you can, though so far I've never managed to do that myself. I look forward to the day that I do, meanwhile dreaming of getting to a convention well rested, showered and generally just relaxed.
When you get back home, once you've kissed your family and slept for the better part of a weekend, it's a good idea to get back to the people whose business cards or other contact information you've managed to accrue during your trip. Not only will that make you remember them better but it will also help them remember you better. And if someone's been particularly nice to you, it might be a good idea to send out thank you cards, though that's probably a topic for another post entirely.