If you contribute to an open-source community, there will be an "opportunity" that you will represent the community to a conference. You're expected to staff the booth and talk to people about the software.
For some people, it looks like you are traveling and having fun. I have news for you. It's not like that.
We are going to see some tips on how to survive the booth duty.
1. Contact the booth managerIf you're not the booth manager (usually you're not), then you need to contact him/her before you travel. This person is in charge of shipping all the swag to the exhibition-conference hall at the right time, getting everything put together and taking things down afterward. Usually, this person organizes the shifts at the booth. So you have to check when you can have your brake, ask if there is a special "strategy" to promote, etc.
2. ClothesMake sure with the booth manager if there is a dress code (so you need to carry a suit). If not, then make sure about the same T-shirt. Wear a comfortable top (T-shirt or hoodie) with the project's logo. It's good for the project that when you'll have a break or when you go for a walk to check other booths, you "advertise" the project. There might be people to see the logo and ask you, so you can point them to your booth.
Carry with you another T-shirt just in case of an emergency, so you can change (also carry a deodorant).
Regarding pants, wear also something comfortable. Jeans are fine but if it's summer, then a short is OK.
3. ShoesWear comfy shoes. This is the most important tip. You are going to spend a lot of time standing up. Most of the conferences are 2 days long, so you're going to be getting very sore feet. A pair of shoes with cushioned soles are the perfect choice for the situation. If there is a dress code, then be sure to wear high heels during your central presentation and then have a second pair of shoes for your booth duty.
4. Help with setup/breakdownIf you're not an employee of the open-source project company, then usually the company behind the project (or the companies that sponsor your open source project), paid part of your expenses. They expect you to stuff the booth but also to help them set up everything before and breakdown everything after the conference. Having good "relation" with the booth manager means also help with these activities. Ask questions like: "Where would you like this?" or "May I carry anything?". Be different from the people who turned up two minutes before the show was due to start and made ill-advised remarks about the sign not being entirely straight on the front desk.
5. Don't over-police the swagSwag means "give-aways". Usually, swag is a discussion opener. If the visitor is aware of your project, then he/she wants to get stickers for the laptop. Let them get more that one, because they usually get some for people back home, for people who cannot attend the conference or for LUG members. Experienced marketers realize they'll just need to box everything up at the end and ship it back, so they might as well give as much of it away as possible.
6. Save some swag for the second dayMost conferences have the majority of visitors during the first day. Usually, they get most (sometimes all) of the swag. The project run out of some swag the second day. That's good because, during the breakdown, there are fewer items to ship back to the company's office. But it's bad because the visitors on the second day, won't be able to get some swag. So save some for the second day (Pareto principle: let's say 80% the first day and 20% the second day). If you have some swag left before the breakdown, take a selection of your best swag around to other booths on the floor and see what you can swap. Your project's swag may seem utterly useless to you, but there's a good chance (particularly if your marketing people know their thing) that other people might want it and will be willing to give you some of their swag in return.
7. You need a big suitcaseIn other words, you need an empty big suitcase. Why? Because you'll get swag from other projects or even from your project to use back home, to share with other open-source friends-communities who couldn't attend where you've been.
Regarding how to behave at the booth, you can check the video from an openSUSE conference:
And another from my friend Jos: