I--like most creators, I'm supposing!--have an abandoned webcomic in my proverbial closet...even though I had a good idea of the end goal, without a firm outline I quickly got behind and lost motivation.
So, with Imaginarium I made SURE I had the whole thing outlined, thumbnailed, and most of the linework done before I posted the first page--and that's really helped me keep on track! (Also, AAAHHHHH!!! It's the front page spotlight today!
I'm so honored!)
I'll second what others have said about starting with a smaller project that has a definite ending. You'll be more likely to actually finish it, which will be a great boost to your confidence. I'm a great starter and not a great finisher, so now that I have completed several different personal illustration projects and have a webcomic/graphic novel firmly on its way to completion, that's helped my confidence in my "finishing abilities" a lot!
Also, with a shorter project if you decide the format/art style isn't really working for you...well, you can just try a different one on your next project! That's what I'm trying to do right now; figuring out what I'll do differently with my next project to make the process even easier and more intuitive. ALL THE SHORTCUTS! 