I don't think you're dense, I just think you haven't done something of this scale before, that's all. You don't know what to do yet, and you're asking for help because you're a more social artist rather than a vacuum artist.
Every artist is different, every author is different, we all have different ways. Some of us need to lock ourselves in a cabin the woods until the first 7 drafts are finished (that's me) other's are social artists and like to work in a team (that might be more you). Sometimes we like to talk about projects more than actually doing them (most of the time) and we use that as a form of procrastination--this is also completely normal.
My suggestion is that instead of trying to run a marathon all at once, break down your project into manageable pieces and say "I'll do this much, see how it goes, and if it isn't going...I'll do something else for a while." I know you think that this particular comic is the best thing you will ever make, but it's not. We are all made of many comics, and whatever you make after this one will be even better because of what you learned while doing this one, trust me. Don't be afraid to try stuff out, mess around with it, and maybe even let it fail, because even starting it at all is a form of success--it's a personal project, for your learning, just for you.
And as far as being worried about only making comedies--I'll have you know I was a very emo child and adult and...maybe still am...and never thought I could ever make a comedy...but then I surprised myself and decided to write humor one day. It took a while, it took a lot of writing, but now at least some people think I'm funny so I guess I'm figuring out--so just...this stuff doesn't happen overnight, making successful incredible comics doesn't happen all at once. You can only change and grow by doing and making some flops here and there.