The advice of knowing your material really is extremely important. Memorizing what you have to say generally comes across as forced and unnatural. I generally like to have an outline of what I want to say, perhaps with some notes to make sure I don't skip over a the major point, but other than that I make sure I know the material well enough that I can talk about it casually. This is especially important if people may ask questions in the middle of your presentation rather than just at the end (if at all).<p>There is the extreme where you memorize and script it out and practice it so well that it comes off as totally natural, but I have yet to take it quite to that extreme.<p>Practice your presentation alot, in front of at least one other person. It will make the specific presentation better and your general presentation skills will increase as well.