It's really difficult to pin down down exactly where/how/when creative ideas can strike. For me, they seem to come out of nowhere, usually at the worst possible times (while I'm driving(!) or running some all-important errand that can't be stopped, in order to write down this stream of ideas).
But what about a conscious effort to be creative? Why is it that when we try too hard to be creative, the ideas dissipate, or fall flat?
I have a couple of techniques here that work for me. They're each one step below "trying too hard":
1) sitting down and opening my brainstorming document and reading back over previous ideas. More often than not, just immersing myself back into those original ideas creates newer ideas, and the juices start to flow.
2) letting my mind "go there" - as I'm going about my day, I allow my mind to drift (notice I didn't say "force" my mind, because that's when I usually run dry) and to think about the characters, mull over the story, in general. No pressure, here - just setting my mind on the book throughout my day. A sort of "relaxed" focus. Many times, when I do that, I'll begin to think of NEW/fresh ideas, and they slowy start to tumble on top of each other, one-by-one. Then, of course, I scramble to find a way to write them down. :-)
*edited to add: I just found this quote at a literary agent's site. Exactly what I was saying (but better-worded, lol). Great timing, no?
I don't find ideas so much as they find me. A writer needs to be available to the lightning that, if he or she is lucky, strikes. ~Frederick Busch