I don't know what it is worth, but the advice I was given was to
- Read the summary of the proceedings as soon as it is given to you (bring your laptop, sometimes it is on a USB stick)
- See which talk may interest you, read the abstract+paper if you are interested
- Then listen to the talks that you are interested in, after having read the paper (keep the paper open during the talk in case you need to catch up)
- As much as possible, go talk to people, meet new people, especially people working on similar stuff, ask question.
During the talk you are not so much interested in, you don't necessarily need all the pre-talk stuff, but always have the paper about the talk open, otherwise you will be lost at some point.
Anyway, I think the definite focus would be \begin{cliché} To get as much as you can from this experience \end{cliché}
but not only by listening to talks, also by talking with people, asking questions (to anyone, do not be afraid, usually people are really open to discussion even if they are well-known (might be busier however)).
Final advice, be careful, there are many talks so it is easy to lose focus. Some will be much more important for you; it is better not to follow a talk you are not interested in and fully follow one you are interested in than follow half of them (IMHO).