Well, it depends..
I make sure any of my food or smellibles (lip balm, toothpaste, etc) are not in it, I hang or store those - in my case in an ursack because I'm often in bear country.
Once that's done, if I am in my hammock, I typically take out anything (glasses, spare clothing, etc. and hang my pack from the head of my hammock.
If I am not in my hammock I have several options. When I'm going pretty light on the ground, I often have a 3/4 length pad, in this case I'll often put my pack under my feet when I sleep.
If not, and I don't have a hammock to hang it under, I will sometimes leave it in a gear vestibule of a tent.
If there are trees handy, I will sometimes hang it from one nearby, but usually with a green garbage bag upside down over it and just the topstrap pulled through a hole in the garbage bag - so it doesn't get soaked if it rains.. If I am in a backcountry campsite with bear hangs, I often do this and leave my food bag in the pack, running the whole thing up the bear hang.
So there, there's a few ideas for you. Just don't leave it with food in it where critters can get at it. I also don't personally like to leave mine outside on the ground, due to the possibility of rodents chewing on the (often sweat salty) pack.