Finally have the time to drop that review you had asked for a few weeks ago.
So I've gone through your gallery and I'm just going to start off by saying I don't like to critique webcomics. They're really an entirely different beast from critiquing art and they're not something I'm super experienced with analyzing. That being said where you are currently in your work judging from your most recent submissions I can give you some pointers.
I'm going to do a breakdown of your most recent submission since its probably the best indication of where your work is right now and where it will be heading in the future.
Your backgrounds need to be better realized. In many cases they're just a single color, which isn't bad, but they aren't filling the background completely the edges aren't filled in leaving white gaps between the background and the characters/ props – this makes the whole page look sloppy and unfinished. Taking the time to fill in the colors all of the way will go a long way in your presentation. The same goes for the colors on the people and the props.
Your lines also need to be cleaned up, in many instances they intersect and create little crosses and while this can be used to create a certain style, here I really don't think its working; just take the eraser tool and clean them up a bit it shouldn't take too long
Those white semi transparent blobs you use for highlights need to go for sure. They're not very appealing and take away from the scenes, its good that you're shooting for shading, but you need to pick highlights that work with what your chosen colors – just throwing white on there isn't going to cut it. A good method for highlights is to add some light yellow or white to whatever color you're highlighting then with the newly mixed color make the highlight. Same goes for shading but switch light yellow/white with Blue/violet/black depending on the styles you're shooting for. Also your highlights are applied with no consistent light source. Do some studies of objects under a sing strong light source to work on this.
Your character designs themselves work pretty well for a comic strip style, they definitely have that sort of Charlie Brown, Garfield, calvin & Hobbs look in the shape and eyes. I like the way you've done their mouths and eyes as well - very expressive. Cleaning them up and working on your strokes would enhance the emotion. Try working with quicker strokes and maybe testing out different brush types as well. Doing some gesture drawings is always a great thing to do as is studying up on the line of action. These studies will help you get the most out of your character poses.
The way your characters occasionally overlap into other panels isn't working. Its a common practice for interesting panel composition, but you're not going far enough with it. Right now its just an elbow here, or the edge of a shoe there. To really make it work you need to go all out with it, make larger portions clip in, make it look intentional otherwise you're viewers will think it was an accident and probably not respond favorably to it.
Your text bubbles as they are could use some work too. Make the bubble larger, right now the words are touching the edges of the bubble in all of them the words generally never do that, it makes it cleaner and easier to read and separate from the surrounding panel.
Last thing, give your comics a blank white border around the page, half inch or whatever relative pixel equivalent is good this will focus the action and give the viewer a solid contained space to view. When it goes off the page it can get a little unfocused. Also make sure those panel borders are straight, or if you're going for a look though go all out for it so it reads as intentional.
Keep it all up man, most of these issues stem from a place of not taking the time to do clean up and can easily be fixed. Other parts will come as you draw more and work to improve.