So, failed to read the rules and clearly messed up on a couple points on the last attempt. I'm very sorry about that, and I hope nobody hates me too much already to respond to this attempt.
Here's an
actual image. This was done on a Wacom Bamboo Tablet in GIMP, and would look much worse if not for the miracle of CTRL+Z.

I'm not a terribly experienced artist. I've been using this equipment for about a year. I've done a few panels for comic concepts that never went anywhere, but this is new, and I do consider it a personal best, whatever that means. I'm particularly very proud of that dumpster back there. So, naturally, I'm throwing this in here to get humbled.
I'm interested in knowing if anything just looks ... amateurish, I guess. I'd like to know if you see anything that betrays a lack of technique knowledge, either in cartooning in general, or perhaps the use of GIMP or similar software.
From a practical standpoint, I'm a noob, and I want to know any reasons my artwork hurts your eyes.
Posts
Do you have some goals for your work/your comic? Do you do any drawing outside of your comic? I would check out the Questions/Tutorials thread, there are a lot of tools for improving your general skills as an artist. I encourage you to post more work, and post drawings that are more than just your webcomic. Don't just come to get humbled, there's a lot of people here who will try and push you forward!
Also, welcome!
I kid. No, dude, not too harsh at all. Thanks. Worst thing in the world is thinking you're great at something and never having anyone around you to tell you otherwise. Not that I thought I was all that great.
I'll definitely check out the questions/tutorials thread.
To give you a hint about just how amateur I am, I'm actually happy to finally know what to call that dang white space from the fill tool. "Halo" is easier to type than "dang white space." While it's my bane in general, the one exception is the beard, where I'm actually trying to set it apart from other objects in the scene and not let it blend in. (Rather important bit of context: it's sentient, prehensile, and a bit unfriendly.) But perhaps I need to do that more neatly, in a way that doesn't just look like a happy accident.
My goal is honestly just to have an audience that enjoys reading (and looking at) my work. Having the hosting costs be self-sufficient would be great, too, but first things first.