I believe there's something to what PaleRider has suggested, but it may not be for everyone. I know some people's dreams tend to be fairly mundane, like a distortion of their waking life. And here RC's should work well, because they "carry over" into the dream world. Personally, however, my dreams rarely have anything to do with my waking reality... otherwise I'd be performing RC's as often as I do when I'm awake. So something more fundamental is required. And it's this that led me to experiment with the "omnipotence factor." Essentially, we are omnipotent for a third of our lives, only we don't realise it. Trying to exercise this omnipotence throughout the day (to verify one's "location") may carry over more easily for some than standard RC's. Floating or flying dreams should also then alert the dreamer to their omnipotence, and therefore their "location" (in the dream world). That's what happened to me, anyway.

It's all very frustrating though, which is what led me to experiment with supplements instead. I want guaranteed lucidity and I want it EVERY night!!