I once had an art teacher tell me;"When you're sitting with a blank sheet of paper in front of you...don't spend too much time thinking about what you are going to draw or create.  Just begin to write down words and more words...whatever comes to your mind - as it relates to the project you're working on."

I was amazed at how many related words I was able to write - soon I was beginning to illustrate pictures to fit the words.  Before I knew it, an idea had formed.  I have used this exercise when teaching others and it has helped many people.  I hope it helps you.