you have to pack up all your food in special bags, then they want to walk through the house and check out EVERYTHING AND EVERY ROOM, even drawers.
if you have a big safe they might even want to look inside (dead body check), or they will refuse to do the job, and prolly still charge you.
so good idea would be to take guns/valuables to a friends house.
+1 with staying with them every second they are in or around your house, make sure they place chains and locks on the doors, dont leave the premises until they do. there should only 1 guy in the house, the guy that does the gassing and house check, no other worker needs to come inside.
also turn off your gas lines, there was a house a couple years ago that had a gas leak on the outside of the house, unknown to owners, the tent trapped the gas until the place BLEW UP!!! the house was matchsticks and it blew a couple other houses off their foundations, not to mention all the other damage in the area for a couple hunderd yards.