Over the years I’ve attended quite a few conferences: ones for writers, ones for readers, ones for all publishing industry people.
My first piece of advice, the wisdom gained from watching people’s behavior at a multitude of different conferences is: Don’t get drunk in public. If there’s lots of free alcohol and you really want to drink it, take it back to your room. Trust me, doing a bunch of stuff you can’t remember the next morning is not good for anyone’s career. Also, even if you can’t remember it, chances are others will. And there’s also the possibility of seeing yourself on YouTube and Facebook...
Secondly, be polite. It’s very likely the staff and volunteers have worked extra hard in the preceding weeks to make the conference happen. Undoubtedly things will go wrong. Speakers will be late, or worse, boring. Someone will have thrown up in the bathroom you need to use. The line for the free lunch will stretch around a city block. Use the wait in the line to talk to people. Tell them about your book, or the one you just read. Make friends, influence people. Have fun where you can.
If you are an aspiring author and plan to pitch to an editor, do not follow them into the bathroom and start talking about your book. This has actually happened to several of my former colleagues and none of them appreciated it. Wait until your official pitch time, then smile, take a big breath, and talk about your story and why the editor should read it.
Conferences can be wonderful times of fellowship and fun. Enjoy the people and events. Learn from the forums and workshops. Party with your friends. Just remember you want to be able to look these people in the face again next year.