The next level of information is the detailed program that is available at the meeting, or is mailed in advance to preregistrants. This gives the titles of each talk in a session, and the names of the presenters. Sometimes it is fun to hear a talk by someone whose name you know. It might be the author of a text book you have used. Or maybe someone who has written an article for Math Horizons or the College Mathematics Journal.
Many students go to hear their friends give talks in student sessions, or their teachers.
You can also pick talks to attend based on the titles. However, like judging a book by its cover, this is not always an effective approach. It is often hard to tell what the talk will really be about based on the title. The detailed program may also contain more extended descriptions about the organizational theme for contributed paper sessions, special sessions, panel discussions, and so on. These descriptions will not tell you what any particular presentation in the session will cover, but they do give you a pretty good idea of the kinds of topics that can be expected.