What's your best advice for giving talks and presentations?

I have to give a very important presentation to a small group of people on Friday.

I do not like giving talks.

I practiced the talk for the first time last night, and broke out in a sweat while I was talking.

Aside from generally being terrified, I have specific problems that I need to figure out how to address: I tend to speak way too quietly when nervous, and I fall back on reading off the slides as a crutch instead of explaining. Much as it bothers me, I have a couple of very text-heavy slides that I plan to just read, because I don’t want to freeze up and lose it.

Any advice?