I second recommending the Monroe Institute audio guides. I nabbed them off BitTorrent years ago, and I play a few of them on an iPod shuffle while falling asleep. It's worth seeing past the New Age (rhymes with "sewage") stigma--the point isn't some non-sense about metaphysical "energy", rather the point is to get you used to putting your body into a quasi-hypnotic suggestive state where visualization can be much more active in your perception.