Here's my method:
*Create 3 to 4 drawings, "keyframe" drawings, in which you want the character to turn to. So layer 1 would be "front", layer 2 "half front, half side" and layer 3 would be "full side." Also make sure they're position so, "front" is at the top, "half front, half side" is middle and "Full side" is at the bottom. Also grouping them might help.
*This is where alot of brain power and patience comes into hand. You're now going to move the points to create the "in-betweening" from keyframe to keyframe (or layer to layer).
*The layer you want to tween to (Half front, half side layer) keep visible, as you'll need this for reference.
*Now edit the points in the "front" layer so they exactly match that layer (Half Front, Half side) and there's your turn.
*From there you might want to fiddle around with visiblity, and camera movements (this can sometime help).
i only use this method as switch layers don't work the way i want them to sometimes. Even when i've made a drawing with the exact same amount of points, it doesn't interpolate like it's meant to, so i find this method gives you more control over the movement.
Because i'm bad at explaining stuff, here's an example file to fiddle with:
Example File
Have fun
(modeling a dude in 3d is much easier then using the drawing tools of moho! to draw a 2d dude )