1. Be up-front about your argument: put your main point at the beginning of the paper and tell the reader why it matters. I can only speak for the humanities disciplines, but we tend to be very schematic in outlining the presentation at the beginning: first, I will define X; then I will talk about its relationship to Y; finally, I will conclude with a brief discussion of Z.
2. Remember that it is harder to digest information when you hear it than when you read it. Your audience will appreciate a little repetition. Remind your reader of your point several times in the course of your paper.
3. Don't assume too much specialized knowledge: the audience members may not be from your discipline, so you need to give them a little background before launching into your argument.
4. Rehearse your talk several times, and time it. Going over your allotted time is the worst of conference sins. It's fine to go under time, though, which just leaves more time for questions afterwards.
5. As you rehearse, note places where you run out of breath and break those sentences up into smaller pieces. Shorter sentences are easier for the audience to digest. Note places where you stumble over wording so that you can revise tongue twisters.
6. If you are presenting a paper, print it in large, doubled-spaced type (14-point) so that you do not need to squint to see it when you are standing at a podium.
7. If you are using technology, arrive early so that you can set it up and test it. Make sure you are prepared to improvise should something go wrong with it.
8. Bring some water. All of us get nervous in front of people and that, along with speaking non-stop for 10+ minutes, can leave you parched. There's nothing worse than getting a raspy throat in the middle of a presentation.
9. Dress for conferences varies, but usually participants shoot for business casual, at the least. For men, this means a button-down and slacks; for women, casual pants or skirts, tailored shirts, blouses, or sweaters. Suffice it to say, jeans are usually out.
10. Attend other people's panels. The audience for panels at professional conferences is usually mostly presenters on other panels. If you want people to attend yours, you should attend theirs.
Most of all, have fun! Remember that the people in the room are your friends and are not there to judge you or your work. Plus, most, if not all, of them know vastly less about your subject that you do!