For me two days before I'll shine up the guitars I'm playing, change strings, and test my setup. I stack it up in the corner until load out. I always bring five things: Amp, Cab, pedal/cable case, and two guitars. When I load out it's really easy to count the five pieces, so I know that I'm set.
Last show I played though.... I broke my routine. Having just changed strings before our last practice five days ago, figured I'd save myself the five bucks. Get to the show, load all the gear on stage and tune my first guitar. WTF!!!!! Broken D string, happened in the case!!!! Changed the whole set before we went on, but that was a first for me, and probably punishment for not following the routine. What's your routine?