Considering the potential expenses associated with attending a Conference (travel, accommodation, food, the conference itself, etc) you'd want to ensure you maximise the event.
Below are some tips that might be able to help.
1) Dress for the Job you Want, not the Job you Have. A conference is not the time to slop around. This includes the cocktail party, dinner and, if you're invited, the VIP event.
2) Get Out on Your Own. Too often young attendees partner up and stick with their buddy, potentially losing many opportunities to interact with other professionals. Or as Dave Sutton says:
3) Two Ears, One Mouth. Listen twice as much as you talk (especially if you're around the top delegates).
4) Aim to meet 10 New People Every Day. Seriously, set that goal. Over 3 days that is 30 new contacts.
5) Maximise Meal Times. Not only for the protein but for the conversations that take place. Guaranteed you'll pick up great information. Or make a new friend.
6) It's an Endurance event, not a Sprint. Pace yourself, especially on the social side. There are a number of delegates who've peaked early and have nothing in the tank on the last day.
7) Spend Time with the Sponsors & Exhibitors. Firstly, if it wasn't for them, the costs of the conference would probably sky-rocket. Secondly, don't just think of 'industry contacts' as other delegates, commercial contacts are vital too.
8) Sit at the Front. Your engagement will be higher in the front row. If you don't believe me, compare how many people check their phones, twitter, email, etc. in the front row versus those in the back row.
9) Don't Think in Terms of 'Right or Wrong'. If something is presented which disagrees with your paradigms, try to understand why it worked before dismissing it. Even better, think 'Who, where and when can I use this?' and save it for later.
10) Report on the Info. If your team, club or academy contributed to your conference attendance write a report detailing what you learnt. Circulate it amongst the performance staff and the decision makers so that it becomes valuable for the organisation, not just you.