Rehearsal
It is not enough to just review your script and notes. You need to rehearse your presentation.
Preferably, you should rehearse with your slides/visual aids in the room you will eventually present in. Since that might not be possible, rehearse in front of a mirror or friend. It is important that you actually say the words aloud, hear how they flow and refine your script. To really get a sense of your weaknesses and strengths as a presenter, film yourself rehearsing and scrutinizing the video.
- image credit: "Anna Karenina at JAW 2011" Some rights reserved by Portland Center Stage
Technology
If you plan on using any technology, equipment, or software during your presentation, test it all out before the big day! There is nothing worse than starting off 
your presentation with a broken projector, low battery, faulty link, or corrupted PowerPoint file.
Also, always have several backup plans in place. For example, bring an extra laptop with you and back up your presentation on a flash drive and in the cloud.
Image Credit: "Fixed" Some rights reserved by Don Fulano
