I've always been a fan of Russell Crowe. He's enormously talented and I love his movies. I happened to see a video on YouTube of him being interviewed for "Inside the Actor's Studio." This was done a few years ago, but something he said about character really struck me, and I realized that it can pertain to writers and our characters, as well.
Here's one nugget of gold: "Serve the character, not yourself." In other words, take yourself out of the equation. In your novel/short story/etc., have your character do what your character would do - not what YOU would do in that particular situation.
Here's another really good piece of advice:
"You fall in love with your character, you miss out on the opportunity of showing up their faults. Be objective about the character - it's those faults that make that person an individual...make he or she a human being."
Bingo. In acting as well as in writing, our characters need to be fully human. Don't fall in love with them and overlook their faults. Your character will come out as one-dimensional and unbelievable.
I love the parallels between creative worlds - acting, painting, writing, photography, etc. There's so much knowledge to be gained from taking a glimpse into a creative career that is not your own.