I attended an event last weekend that reminded me of two important leadership lessons:
(1) Never apologize for a project, event or group in advance. All you're doing is making yourself feel better and your project/event/group feel worse. Most of the time your audience can't tell the difference anyway, but now you've brought attention to it and they'll be focusing on the wrong things.
(2) Never try to build up your project/event/group right after you've apologized for them (see #1). Why did you just spend five minutes telling us it wouldn't be as good as you hoped and now your trying to sell us on the brilliance of your project/event/group? We didn't buy it before and we sure aren't going to buy it now.
Confidence breeds confidence. As the leader, proceed with the confidence and surety that this will be the best possible execution of the project/event/group that can happen at this particular moment in time. Own the moment. Afterwards you can spend time celebrating and evaluating. Don't spoil it for everyone else - work to create a defining moment, even if it's a small one. Your audience will remember that little defining moment much longer than they will your entire performance.
Finally, evaluate why you felt compelled to use #1 and #2. And remember, people end up where you lead them.