I'm going to start with the hardest to work with element you are working with ... your 'logo' ...
it doesn't say a two z sign shop. it says delta two zeta (because you actually didn't use an A you used delta which makes 'z' read as zeta) sign two shop or delta zeta zeta sign shop shop. it's convoluted and difficult to read properly. Then, you are using what looks like cell phone bars to either side ... at a quick glance I was half expecting you to sell cellular services as well as signs.
Now, as for the comic cells, I'm actually fine with them ... but if you are going for the illustrated comic feel, why the heck to you have such wonky hard lines for the cells with cheesy stock vector art for the contents when you could probably create your own with a lot more feel and emphasis than that without resorting to random missles and 'pow' effects when there isn't anything to say 'hey, something is going on here' ... make your van tell a story, the title of that story is your logo and shouldn't be contained to a single cell, it's the fricken title. If you can't make your own where all you need is some solid black and white ink work to define a LIMITED pallet ... there are plenty of freelance illustrators that won't charge you much to make you the art you need to get to where you need to be. Tell your story! make it personal! most importantly, make it custom! Your logo says GRAPHICS and DESIGN ... two different things ... show them how you roll or find someone who can. There is no shame in hiring someone to do what you can't.
I would put your logo smack dab on the door to first side panel prominently, and have a hero beginning to fly across your back half over head the logo with his fist held high above his rippling man scaped mane with the index finger prominently thrust outward to say 'I'M NUMBER ONE!' .... NO pointing woman who looks like she's shocked to see a hobo peeing in the streets, no random bomb, no pow or thing going pow behind your services, limit your pallet ... it's a comic page, not a prismatic peep show of mediocrity. DO use forced perspective, do make it look like your hero is having the time of his life and is full of energy, do make your logo not feel like an after thought (redesign if you must), DO find your style to showcase the artwork (with your logo ... go more techno than golden age). DON'T use wonky panels that have no rhyme or reason to them, make that negative space count as much as the positive space, make your hero break out of the cell as though he isn't contained by arbitrary limits to be number one, make the panels background work as important as what you are trying to showcase in them be it your shop info or just a filler panel between a window and another important panel ... this is where your story shines and makes customers eyes linger. Don't be afraid of detail, the idea behind a comic is to show an initial story of action then as you read across it your eye catches the details and that (at least now) is the difference between a good story and a great story is continuity and the little things to make a person keep looking at what you have made.
And for the love of all that is unholy, why are you using a stroked outline on the text that isn't consistant? one panel is red, gets a black stroke and white lettering ... another is cyan, gets a white stroke (which won't really show up cleanly) and red text ... then another design that is flip flopped. make your text consistant. info gets read left to right, up to down ... panels flow the same way, and don't tilt straight text ... looks wonky. Also, if you stroke your text, make your logo stroked as well. applying a glow to the logo makes it look silly if your text is stroked in a schizophrenic way.