The famous 'spinning' technique can prolong lucid dreams. You just spin your dream body like a top. It has 'kind of' worked for me in the past. Charlie Morley delves into meeting your subconscious and OBEs in his book Dreams of Awakening. It's a little new-agey for me; not convinced there's any empirical evidence that your consciousness leaves your body during an OBE. I think all evidence points to consciousness being a direct manifestation of the brain.