Finding the Pose
Once I felt comfortable drawing the characters, I did some thumbnail sketches for each character's pose, searching for the best character-appropriate gesture for each. It's worth noting that when I'm doing gesture sketches like this, I'm working small and fast. I'm not worried about proportions or details--that comes later. This is all about finding the pose.
Veronica is the rich girl that pretty much gets what she wants. I decided to give her a hand-on-the-hip pose that emphasized her confidence and stylishness. For her outfit, a cute flirty dress, clutch handbag, and a bit of bling. I briefly entertained the idea of a more illustrative shopping scene for her (with bag carrying Archie in tow), but decided to stick with standalone poses.
To contrast Veronica, I went with a sportier pose, and jeans and jacket outfit for Betty. I got pretty far in the drawing when I realized the pose was a bit too similar (hand-on-hip again) to Veronica's.
Keeping the keywords "cute" and "sporty" in mind, I started over. Of these, the first two I did (upper middle, upper right) weren't right at all for Betty -- too sexy; too cutesy. After that, I stopped and reconsidered the character. Sweet and sporty. I liked the gesture of Betty twirling a finger around her hair to showcase her ponytail, so I kept that in the rest of the sketches. I ended up going with my third attempt (first sketch on the top left).
Archie's your average, nice guy character that everyone gets along with. For his pose I decided to show him "just hanging out".
Jughead's the goofy comic relief character. To capture his cartoony mannerisms, I tried to push his poses towards the extreme (without going too far). I thought it would be funny to show him tossing an entire burger in his mouth the way you might with a piece of candy.
Polishing the Art
Once I had my poses selected for each character, I printed out the sketches at a larger size with blue lines so I could do a clean pencil pass over them with their proper details and proportions.
And here's the finished results!