I have my mom check the temps every other day or so with the temp gun, and make sure probes are all secured....

+ 1 leah  depending on how long you will be away  you may want him to mist  once or twice if needed

My instructions for snake sitters include a number of dichotomous-key-like questions, including the following:

1. Is the ambient temperature (in the herp room) between xx-yy degrees Fahrenheit?
   
   • If not, then...
2. Are the lights and/or heating devices for each enclosure turned on/off, depending on the time of day/night?
   
   • If not, then...
3. Does each enclosure have clean water that is completely free of substrate or feces/uric acid?
   
   • If not, then...
4. Does every specimen look like it is doing well [this part obviously assumes some experience with reptiles]?
   
   • If not, then...
5. Is every enclosure clean and entirely free of feces, uric acid, or shed skins?
   
   • If not, then...

In addition, I separately list which enclosures need to be misted, and how often they should be misted. If feedings are involved, then my sheet immediately becomes much more complex, with detailed instructions for the scheduled date of the feeding, and the exact size and type of prey item to be used. I also frequently check in with the snake sitter, just to have additional peace of mind, and to address any potential problems that may arise early on.

+1 to everyone who has posted so far. The only thing i would add is to do a quick walk around before leaving the room to make sure all enclosures are secured properly.