0. THE FOLLOWING MAY BE PARTICULAR to Jewish worship services, which are the only sort I’ve led (not counting five weddings and various improvised blessings/moment-summonings). But I’ve tried to adapt the advice for anyone whose worship tradition includes structure and text, and who finds oneself in the liturgical spotlight. Hope it helps; I learned it all the hard way.
1. Know your material. This may sound fairly obvious, but I mean it in a deeper sense: The service-as-conducted is a living breathing entity whose skeleton is the service-as-written. Know the latter like you know your own breathing. At least know how and why it’s structured — what each piece hopes to achieve, and how it leads to the next — and, most importantly, what page everything’s on. (PostIts are a big help here, as is having your own siddur (prayerbook) to notate.) Likewise, see in advance to the functioning of candles, wine, microphones, guitar strings, etc.; there’s nothing like a last-minute surprise on a solemn occasion (ah, but see thought #4). (And if you’re feeling terribly insecure, keep in mind that for group readings you really only need to emphasize the first five words. It takes that long for people to catch on and start drowning you out.)