For what it's worth, character design and construction is always a challenge. In particular, I've had plenty of trouble trying to build decent looking turn-arounds for the heads. Having things come out even (ears/eyes level, etc) and in decent proportion are an ongoing challenge for me. I've been working on Polly Possum for a while, trying to get the face just right. I had the front and profile working for me, but simply could not get a quarter-view to come out looking decent. Then it hit me -- draw an overhead view, and check the lines of sight! The guides from the middle left head gave me what I needed to construct the top right head. Then things started making sense.

Once I had the blockhead (no emotion distortions) turn-around working, then I could play with squeeze and stretch in the lower right.
This is probably old hat to (much) more experienced artists, but for me, it's a find I hadn't (clearly) seen in the various How To references I've been using. Enjoy!
So -- experienced artists -- what gimmicks/tricks/techniques would you like to share with the rest of us?