Jumping in the air and trying to fly, or at least float, seems to be a good RC...

Well, not if it's when you're in 3rd POV. Those dreams are hard to find an RC for, I do know that when I do have 3rd POV dreams [which have become more frequent recently], I naturally become aware that I'm watching people. Instead of becoming lucid though, I tend to somehow become weaved into the story and get 1st POV, so... if somehow you can do that [I have no idea how] then you could try a lot of the other RCs people have suggested.