1) Signed contract.
2) Always carry your own direct boxes, mic's, and associated cables. Don't forget guitar cables.
3) I want the equipment set up, sound checked, and ready to go 2 hours before the gig. There is nothing that will start to get you jangled like wondering if the damn sound is right.
4) Bring your own sound person. If this isn't possible, then sit with the sound guy and give him/her the basic information about any peculiarities in your setup. Ex: I use an LR Baggs dual source set up in the stereo mode i.e. one channel for the ribbon transducer, one for the mic. I always let the sound person know that I have the bass cut set way down and that they should adjust the bass in. Another thing about this setup is that the internal mic should not be run through the monitors. Resolves the feedback issue. Also let them know that once the monitor mix is set, it is not to be tinkered with, and then make sure you have it where you want it. The only adjustment I want made on that monitor mix is the master volume, unless I tell them otherwise. Help them set the mains about where you like them, but let them fine tune it. The sound in the mains is theirs, the monitor mix is yours.

By being done early, it gives you time to decompress, run over last minute stuff, and mingle with the crowd to get a sense of what you need to do to entertain them. That also allows you to set the mood for the evening.

Mick