I've talked about beating writer's block and how I create a character outline for my projects, but here's another thing I do...
If I don't have a clue as to what my character looks like, then sometimes, I don't know who they are.
When that happens I go to an artist and we bat ideas back and forth until I get a clue as to an actor or person similar to my character. Then I commission a portrait of my character and let the artist help create that person in my mind.
To the left is Kleck. He's the first rendition of a character I'm working on for a were-wolf romance. Kleck is a secondary character but his importance to the reader is vital. But before this line drawing, I couldn't imagine his physical form at all.
Just another trick to beat another form of writer's block. It's also an awesome feeling to get pictures of your character. A one of a kind image of the people inside your brain. For me it's worth the expense.