I think Lord Vincent's advice is good! The first step of writing all my ideas down helps me a SURPRISING amount, just because then I don't have to hold them all in my head at once -- I know it's written down and I don't have to think about it all the time.
Honestly, the best project to do first is the one you (a) are the most excited to work on and (b) have the most figured out. If one is the most fun to work on, focus on that one. If you're interested in all of them but not sure which to pursue, pursue the one that's the most solid or has the most developed.
And don't feel bad about jumping around, either -- like, you don't have to fret about whether the comic you choose to start on is The Best Choice. The comic I ended up making wasn't the one that I was originally planning to make, but I kept getting ideas for it and being really excited to work on it and eventually had enough ideas that I could start really developing a story for it, and I didn't feel that way about the comic I was working on at the time, so I changed my focus. If you start on one thing, and then change your mind, that doesn't mean your first work was "wasted" -- you might've needed that first project to warm you up or help you figure out how to tackle a particular problem. And I've known some writers who go back and forth between two projects to keep from getting tired of either of them!
so, TL;DR seconding Vincent's advice, get these ideas out of your head and onto paper, and don't worry too much about which is the one you SHOULD pick. Just start somewhere, and it's okay if that changes later!