For those of you who haven't obsessively followed Brandon Harris's answers on Quora http://www.quora.com/Brandon-Harris-1/answers -- check out his suggestions on how to improve your skills at interaction design and visual design:
http://www.quora.com/Communication-Design/How-can-I-get-good-at-visual-and-i...
A few key tips from Brandon's answer: design is about understanding problems. Look at problems and try to re-solve the problems you run across every day, both simple and complex. Research why people created existing solutions and made certain decisions, and think about what you'd do differently. Learn to communicate your designs, and practice a lot.
Brandon, thanks for the writeup.