- Read your work aloud to yourself.
- Use "waiting situations" -- in airports, in line, etc. -- to work on descriptions of people.
- Listen carefully to regional dialects and everyday speech.
- Drawing or sketching a landscape can preserve it in memory.
- If you have a character that isn't working, try changing their sex. It can be useful, and "at the very least, it's amusing."
For more tips and more about her appearance, check out this article in the Oregonian.