Flush your system first so you don't circulate all the crap into your new radiator. Use anti seize on the thermostat housing bolts to keep them from seizing up again. Makes taking them off almost pleasurable! Clean the mating surfaces with scotchbrite (where the hoses mount). I like to use a little Dow DC4 grease on the O ring of the thermostat as well (make sure that the relief area where the o ring goes is nice & clean too. We would always spend more time cleaning parts than reassembling them!
Take your time, save the beer for later.