1. Caffeine. Coffee is made, tea is made, mental checklist run through.
2. Restring what needs restringing, then break 'em in (I prefer that a)I not have to retune in the middle of a section and b)I prefer the slightly more rounded tone)
3. Tune up
4. Warm up
5. Review (though this has probably been going on the whole time). What song, what section, what instrument, what order.
6. Plug in.
9. Listen and/or drink coffee.
14. Play again.
15. Play again.
16. Curse mistakes.
17. Shift guitar strap.
19. Move patch cord
21. Listen again/smoke cigarette.
23. Curse weight of Les Paul
24. Pull out hair while smoking cigarette.
24. Drink juice.
25. Listen and feel relief.
26. Rub shoulder.
27. Switch guitars for next piece.
29. Plug in.
30. Repeat prior 26 steps.
31. Find comfortable spot to listen to final takes (ie, sofa, lounge chair, prone on floor-whatever works).
32. Break to eat.
Rules to remember:
No noodling until engineer says it's safe
No plugging in or unplugging until engineer says it's safe.
Do get lost in a good riff going well.
Enjoy the dry take playback - if it's clean and sharp dry, it's gonna smoke when it's wet (for non-musicians: "dry" means sans effects, "wet" means with effects on).
Trust the engineer.
Trust your gut.
Trust your hands, your ears, your heart.