I'm thinking about working on a comic myself, once I get used to my tablet, of course. The first two panels are nice, but the explosion is rough and you should clean that up a bit. That's something I haven't got the hang of either, since I've been redrawing the same picture over and over again for the last two days trying to make it look better. It's bloody frustrating. Perhaps for the writing you could insert text. I'm fairly sure most applications have an option, if not you could just open MS paint and add it. I'm only saying that because you want your words to be neat and straight and consistent, unless you are looking for an effect that involves these things.