Here's a tutorial that shows you how to!
Step 1: STEP ONE-HAIR
Afterwards, you would draw more zig-zags for the bangs. There you go–hair!
Step 2: STEP TWO-FACE
Connect one edge of the hair to the other side in a half-circle shape.
After you do that, you're going to draw Dave's shades. To do this, you'll have to draw two circles. These SHOULD NOT overlap his bangs. I repeat, they SHOULD NOT. Then, you'd connect it with a curved line, sort of like the one you used to finish his head.
Lastly, you'd draw a slight frown, because Dave has only smiled about 6x in the comic. Also we're not drawing noses because noses are overrated. But if you like drawing noses, then be my guest.
Wow okay those pictures stink but I hope you get a basic idea.
Step 3: STEP THREE-BODY
Starting from where you leave off, draw a line down and curve it at the end. Once again, repeat. These will be his arms. Draw a collar by drawing a curved line.
To finish off the shirt, draw a curve a little above the hands. Also, inside the hands, draw smaller curves, unless you want your Dave to have "sweater" paws.
From the edges of the collar line, draw a straight line going down. That's the red part of his shirt. For the record decal, draw a lightning bolt-ish shape (see pictures) and then draw a circle around the outside. Repeat for the other side. Again, do not overlap if the time comes. Then, just shade that in.
I'm really bad at describing this part (sorry!) so just refer to the pictures.
Step 4: STEP FOUR-LOWER BODY
Anyway, draw a line down, similarly to how the arms were drawn. Draw a curve going outwards and bring it back in. These are his jeans and shoes. Repeat on the other side. Then draw a super long "T" in the middle.
For his shoes, draw a curved line where his shoes seperate from his jeans. Then draw two small circles, and fill everything else in.
To draw some extra things onto his jeans, such as pockets and seams and such, you'd draw two curves about a centimeter or two (really, who's even measuring?) from the shirt's ending, one on each sides. Those are the pockets. Finally, draw little dashes along the outside and near the "T" for the seams.
Finally, a little thing I do (which is optional) is refine the knees by drawing shapes that look like this: > <
Step 5: CONCLUSION