I helped to lead the service Friday night. (Someone later asked me what the occasion was; I said "I asked". Also, it's part of my continuing education.) I'm happy with how it went.
My rabbi and I divided up the service, the way he usually does when there's a second rabbi on the bimah. (Now that our associate rabbi leads another service earlier that night, he's not usually there now.) In our pre-service huddle with the cantorial soloist, for a couple things that she normally does she asked if I was doing them and I said no, the goal was to fit into a regular service rather than being "the Monica show". That might have scored me some points. I mean, yes, I enjoy leading an entire service (and loved the chance to run services, including a bar mitzvah, one week when we had no rabbi present), and I've got the skill to do the cantorial parts too, but part of leading a congregation is fitting into the structures already in place. We've had services where some special-interest group (like the sisterhood, or the 9th grade, or the social-action committee) takes over a service completely, and they have not been satisfying. (In the last year or so my rabbi has come up with a good solution to that problem.)
I led kabbalat shabbat and kri'at sh'ma. We did one non-standard thing (at my rabbi's suggestion), singing ahavat olam instead of just reading it. Enough people know the tune that we thought that would work, and from what I could see, it did. (The accoustics of the bimah, and my vision, are such that I couldn't actually tell if people were singing, but either they were or they were engaged in listening.) My rabbi led the t'filah and most of kri'at torah, except I did the opening (English) reading we always start that section with. I chanted torah, and he gave the sermon and led the concluding prayers. We came in about 10 minutes longer than usual, which I judge to be roughly: 2 minutes for starting late, 3 minutes for a slightly longer sermon (it was good and definitely worth it), 1 minute (delta) for singing ahavat olam -- and several extra minutes for the longest hakafah (torah procession) we've had in a while. (Usually the rabbi carries the scroll and sets a fast pace, but this time one of the aliyot did, taking a more stately pace. I do not have a problem with this; I'm just noting it, as the cantorial soloist did to me when we got back (she'd had to sing more songs than usual).)
A larger proportion than usual of my part was in English; we do the t'filah (which I've gotten in the past) mostly in Hebrew, but do a fair bit of the earlier parts in English (or English and Hebrew, in the case of sh'ma/v'ahavta). I find that leading English and Hebrew are different. (I think I mean diction here.) I can't really explain it; they flow off the tongue differently, and the Hebrew actually comes more naturally to me, once I'm past the parsing stage. (Give me unfamiliar Hebrew and I will either read slowly or stumble.) Anyway, this is probably a good reason to practice leading English in a public service. I got a lot of positive comments on my reading; good to hear. (Also on the torah chanting, including from the native speakers. I'll take that. :-) )
I had mostly figured out the mic (personal clip-on), until the torah service. I have a problem my rabbi doesn't have: a lack of (ahem) a smooth expanse of level real-estate down the front. He can just clip the mic onto his tie and he's good; what are you supposed to do with (err) hills and valleys? The first time I did this I wore a buttoned blouse and clipped it there, but the mic kept wanting to slide under the cloth. Now I usually clip it to the tallit, and that worked fine until it came time to chant torah and I leaned over the table to see the scroll, which caused some rustling. If it weren't for the hearing-challenged congregants who rely on the sound being piped to headphones, I would be tempted to just skip it -- I can make myself heard in a 400-seat sanctuary, after all. Oh well; we'll figure out a better approach to chanting torah next time. The cantorial soloist doesn't read torah, so I can't learn from her experience there. (There is a standing mic available, but using it tends to block my view of the scroll.)
(Yes, I would rather not be using a mic on Shabbat. Minhag ha-makom, the custom of the place, is a significant factor.)
The associate rabbi was sitting in the congregation (which I only noticed during the torah procession). Afterwards he said he'd be happy to have me lead the early service any time I want to. I said I would love to take him up on that in the fall, when that service is a little closer to sunset, and asked if that would be ok. He said yes, so I'll check back with him in four months or so.
Overall, I'm pleased with how it went. My rabbi will be away for all of July; I wonder if there are opportunities there to do this again. (This week had the benefit of having him see/hear me, so he can give me constructive feedback. Filling in is also good. :-) Our third rabbi starts July 1; I don't know if they're going to have him dive into an unfamiliar-to-him pulpit for a month. He will not be primarily a pulpit rabbi, but he's certainly capable.)