Breathing, stretching (like yoga-style-- not 'just got out of bed' style), and listening to music, all at the same time.
It sounds boring, but it has made for some of the best 'peaks' I've ever experienced. 2nd in my list is replace stretching with pacing back and forth.
I know some people will think I'm joking, but I'm totally not. Next time you're tripping try it out. Something about the stretching or the pacing (whichever you choose) causes me to go into trance a lot easier. To me, since I usually trip alone, it's all about going into a deep meditative state and doing some real work.
If that's your bag, take my response seriously.
Otherwise, what I find during times where other people are there (tripping or not) is that conversation is amazing, and always seems to be steered toward deep subject matter. Problem is, on a good dose, sometimes that's very difficult to do between hours 3 through 5 of a typical 10 hour trip.