Great set of tips from Zach Holman of GitHub on giving talks at conferences.
One thing I’ve found is that speakers who have scripted their talks beginning to end tend to drain the life out of it completely. Find the right balance between being prepared and reading a script. A recital is destined to put your audience to sleep. A less structured talk can work against you too since you’re more likely to miss points or talk fast (which is my biggest weakness) but I’d rather have a lively talk that missed a few details than a boring, thorough one. And if you’re truly an expert on what you’re talking about you won’t need that script.