Questions to ask yourself

Here I must do one of the original sins: explain a joke. Or rather, in this case, a comic.
I find that the best way to tell how your comic’s going to be is answering a few questions:

Is your style of drawing realistic, cartoon, or manga (this actually has a big impact. Realistic, not as silly. Cartoon, silly. Manga, can wildly switch between silly and not silly and no one will care because it features long spiky hair)

Does it have a coherent plotline going on? (Penny Arcade, the most popular comic in existence, refers to storylines as “dreaded continuity and try to avoid it. Coherent plotlines are necessary for realistic and manga comics, and cartoon comics can pull it off quite well if they put their minds to it)

Are your jokes for a niche audience? (such as the popular gamer comics, or political comics. Generally, you can pull off a few niche comics if you make sure that it’s funny, just not as much, if someone doesn’t get it, and you don’t do it often)still

Are your comics frequently one slide (often a visual gag with a tagline under it), a three panel (affords some dialogue), or larger? Non-continuity comics often have one slide or three panel comics.

Can you draw well? Guess what, you don’t need to. What you do need is to be able to make recognizable (if not realistic) objects, and have a good grasp for facial expressions. Facial expressions are a must, they add character to your comics. Also, make sure your characters don’t all look the same, it leads to confusion.

Do you use characters when you feel like it, erratically switch between one-panel, three panel and bigger on a whim, and insert continuity stories when you feel like it? That’s fine, it’s a comic for Bob’s sake.

Do you want to commit to a schedule? If you're doing a webcomic or a syndicated comic, you'll have deadlines. You can get away with filler (a short comic or a drawing) instead of your scheduled comic a few times, but your readers will fast lose interest. Also, if you're a new webcomic, you'll want to leave updates at least twice a week. If you feel like that's too strenuous, try writing a lot of comics in advance, at your leisure, and then using them one by one. You'll have leeway that way.

That's some questions to ask yourself. One of the biggest parts of comic is your uniqueness; find it and cherish it.