The key is to elaborate on every thought that enters your head. Let any ideas strike you as they may, and if at all possible, find an intricate picture (for tripping). Music always helps. It's sometimes pretty intense to play thought-inspiring music while watching tv or a movie. Often the music's message will coincidentally fit the video quite well. Those are a few things that I do to trip out sometimes.
(p.s: ... and The Dark Side of The Moon
does link pretty nicely to The Wizard of Oz... )
(p.p.s: Fear And Loathing In Las Vegas has got to be one of the most insightful and purely trippy movies ever.)