- go up to people after their presentations and talk to them (say what you liked or comment on what occured to you while listening or the like)
- use the coffee breaks to hook up with (random) people. often times at coffee break people are standing around alone, whereas in lunch break they meet up with people they already know. do some small talk, often the past session is a good starting point (were you in session x? how did you like y's talk? i always get so annoyed when people don't stick to their time limits, it's unfair towards the other presenters. my own research is on z, so y's presentation really was interesting to me. which session are you going to next? i was thinking that session 34 sounds interesting because of presenter U ...)
- then afterwards, in the lunchbreak, you can hook up with those aquaintances again. it is always good to know the schedule and to know where there is food. (hey there, i was thinking of going for lunch over at Z. want to come along?)