I soon discovered you don't have to wait years; it can happen a few times a week.
Simple technique: - wait until you've woken up after a dream. (so technically hypnopompic, not hypnagogic, but more powerful imho) - Any dream will do, but be careful not to drift back into normal consciousness (so don't think of work, taxes, todo's, etc) - instead, imagine something fanciful. Like swinging at a baseball in dodger stadium in slow-motion, or, my favorite, imagining you have the worlds smallest record player between your fingers & playing a song you like (funk music is good for this) - stay with the humorous feeling, let it grow awhile - after a minute or two, you should find the dream state has stabilized - once it's stable, and only then, call up a problem or life situation you'd like insight into, or just explore the landscape (what's behind that circus tent?) - try not to get too intellectual or willful, it can dispel the state
NB: no drugs required. But caffeine in the evening can increase the odds of waking after dreaming.