Over time, as my tripping technique has refined, I've found that the only thing really necessary is:
Totally quiet & safe setting, zero obligations, empty stomach, courage, and after you take the substance: sit perfectly still, concentrate on the present moment, and surrender.
Always start each new substance at a lose dose.
Meditating before-hand helps to prepare the mind. You want to get all your personal stuff out of the way so you can go deep into existential questioning.
If the trip starts to get hairy, just remind yourself to surrender and get more curious about reality rather than your petty personal issues or feelings.