Comedy Isn't Always Funny

Starting an improv team is hard. For me, anyway. I've Never done it before, and i wish I had a better idea at how to have useful, constructive practices. I kinda feel like I'm making it up as I go... which maybe, is the idea. But no, not for practice. I want practices to build our skills, and help us learn the art, but it seems like all it really does is frustrate us. It makes me feel like I should be doing more to help the team, but I don't know what to do.
I have all these expectations for myself, and for the team, but I don't know what steps to take to reach them. Individual stand-up is frustrating because of my confidence issues and all that, but I know if I could get myself to do it again, I could do it better because I know what didn't work for me and what situations not to get into again. It would also be easier, though, because I'd only have to worry about myself. I could have my own practices whenever I wanted to.
I do want to do that, but I really want to have an improv team, too. They are two separate art forms that I want to be a part of.