Getting the ppt looking professional is important, each mistake or inconsistency will be noticed by someone, probably your boss.
Practice in front of someone, presenting to one is a lot harder than presenting to hundreds. Practice until you don't really need the presentation, practice in the car, in the shower. Try and practice in the location you'll be presenting in.
Make sure your hands have something to do, don't stand there fiddling with your keys and change or wringing your hands. Clothing – is it going to be hot? Don't stand there with pit-stains on a pale shirt or whatever, you'll feel and look terrible.
I was never a big fan of presentations but the more you do the less they bother you. I got the dubious pleasure of doing a daily 20 minute presentation to 2-300 people inc senior management for 3 months, now I'll talk about anything in front of anyone!