Below is something I sent out to a group of undergraduate students I was taking to the MAA Mathfest Conference in Cincinnati August 2019. Many of the tips are broadly applicable so I thought I would share it more widely.
Your conference trip begins when you travel to the airport. Many people attending the conference may be at the same airport or on the same plane as you. Some of these people could be invaluable members of your professional network and lead to jobs, graduate school, or collaboration. Don't make a bad first impression. Make sure you are cleaned up and dressed nicely. Nobody wants to sit on a plane for a few hours next to someone who has an end of the semester, pulling multiple all-nighters college student funkiness.
At the airport or on the plane be prepared to talk about your presentation at the conference. This is your elevator pitch. The goal is somewhat two-fold. The first is to have the elevator pitch act like an advertisement to get the person to come to the talk. The second, if you are on a plane or at the airport, is to stimulate further conversation right there. Try to build your elevator pitch in layers. Have a one-two sentence overview of the project. If that sparks interest, then move to a 1 minute or so description, that could lead into a 5 minute conversation. Don't forget to ask the other person about their work, too! People like talking about their research. Asking a good follow-up earns many hypothetical networking points, even if you aren't all that interested in his/her work. They may introduce you to someone else at the conference. Finally, don't be afraid to wear a math shirt or have a math pin/laptop sticker showing in the airport. This can be the icebreaker for a conversation. (I once got a free cab ride this way from a retired mathematician attending the same conference as me.)
When you arrive at the conference you should attend talks, panels, and some networking events. The MAA conference has a specific ice cream social networking event for undergraduates Friday night. If you are interested in graduate school, no one will turn you away from a graduate student event if you say you want to ask graduate students what grad school is like. Most conferences have multiple rooms and 1-2 hour themed sessions of 15-30 minute talks. If a theme has multiple sessions, they are most likely in the same rooms. For example, all the undergraduate talks are in two rooms at the MAA conference. Finding out which rooms have the types of talks you are interested in attending will save you time figuring out where to go. It is also a good idea to look through the abstracts, both before online and at the conference, to identify which talks you might like to attend. You aren't locked into attending these, but almost always it seems like the two talks you want to attend the most are scheduled at the same time or during your presentation. This may also give you something to talk about with other conference attendees.
Your presentation is the most important thing for you at the conference. Make sure it goes well. This of course includes rehearsing beforehand, but also getting the logistics taken care of to reduce stress. Find out and confirm the room and time you are presenting. Find this room at the conference center. It is a good idea to have backups of your presentation. In addition to having a copy on your laptop, I like to put a copy on a flash drive and email a copy to myself. In some cases the organizer of your session (not the entire conference) will ask you to email them your presentation so all presentations are on one computer. Make sure your clicker/laser pointer has batteries. You may also be required to use the session organizer's equipment, so be ready to be flexible.
For talks, the session moderator will be sitting up front. They will be introducing speakers and asking the audience if there are questions. Introduce yourself to him/her at the beginning of the session. They will probably ask you how to pronounce your name if it looks difficult (like Skorczewski). If it is impossible to get to your talk at the beginning of the session, try to introduce yourself between talks at least one talk before yours. Having been a session moderator and small conference organizer in the past, it causes a lot of stress wondering if a speaker is going to show. During your talk the session moderator will probably give you some signals if you are running low on time. It is common to see 5 minutes left and two minutes left hand signals. They will probably stand up when you are out of time. If you keep talking much beyond this, they may cut you off to keep the conference schedule moving along.
For posters, make sure you arrive on time to set up the poster and bring your own thumb tacks. During the poster session (~1-2 hours) you should be near your poster most of the time, but it is acceptable to visit other posters at the session for a few minutes. It is not ok to leave the poster session to attend a talk.
Make the most out of your trip. You do not need to attend talks dawn to dusk. At many large conferences there is an exhibit hall with information about jobs, grad schools, etc. that you should visit. At math conferences some of the booths have puzzles and giveaways too. This is also a place to find snacks/free coffee. There may be a tourist attraction in the city you'd like to visit. At a job interview in the future, if you mention you were in Cincinnati for the conference and your interviewer has been there, having something to talk about beyond math that shows you are personable and potentially a good fit at the company. Since you are unlikely to have a car, look up ahead of time what restaurants are near the hotel and convention center. Note that prices are likely to be higher near convention centers. This information can be a good ice breaker for networking with other conference attendees. "I hear restaurant XXX near here is really good. Do you want to grab lunch together?" could be the two sentences that lead to an exciting new venture.
