I saw this list on Visual Bits & thought it had very good points:
I also came across this excellent article in The Atlantic that sums up the mysterious creative process:
The four steps outlined in the article definitely reflect how I usually approach design projects or problems in general:
1. Saturation - expose yourself to as many different possibilities & solutions as you can
2. Incubation - take time to reflect & simply think about the project or problem
3. Ilumination - the often sudden mental lightning strike of an idea
4. Verification - re-evaluate the approach you are taking and weigh the pros vs. cons.