Just how I picture my OFC and her size in comparison to the Governor (David Morrissey's 6'3 or 6'4"; she's 5'3" or 5'4"- that's a large difference).
 
She's pretty much a punk, and all that's missing here are her black-rimmed reading glasses and black sunglasses (Ray-Ban Wayfarers or Aviators, I picture) and the Governor's bracelets (he wore one on each wrist on the show). Also, the background, of course (was really undecided on that, because I imagine reading is their only common interest).
 
As for the rest of her, I picture her with brown or auburn hair set in a french braid, or curled and put into a ponytail with a side braid, I guess.
You can fill in the rest of him from the show, obviously.
 
Also, as a sidenote, I really tried to highlight their differences in the clothing choices. From what I gather, he's a dominant dude (you've got to be to lead a town, though), and as such the widespread posture of his arms, large gait of his legs, and direct boot position reflect that. Even the darker colors are somewhat symbolic. Likewise, the opposite is true for her.
 
Unfortunately, I will never grasp the fact that he's supposed to be insane and evil, so let's pretend he's actually an honest man with good intentions, shall we?