My thoughts... Use it like you would a shared laptop. Check your mail through a web client, after making sure that Safari is set up for private browsing. Never enter in your AppleID information; just use whatever apps are installed on the machine. Don't have pictures or music on it; that's not really a work purpose anyway. And if you're concerned about germs and stuff... As someone else says, have a container of disposable antibacterial wipes on your desk, and when you take the ipad, give it a swipe first.
My GF used my ipad regularly till she got her own. My kids use it when they come over (although I clear my browser history before they do...).
They don't have my iTunes password, and they don't need it. Basically, they use it for a portable web browser and whatever games/apps I already have it installed on there. They don't treat it as "theirs", and store a bunch of their personal stuff on there.
It doesn't really sound like the end of the world... Just don't expect that you'll be comfortable using it like you would if it was your personal iPad.
Clint