Well, since I live in a small 2 bdrm apartment, quarantine is a challenge. For any new snake coming in I treat the tub with PAM and set it up in the office (since my main group is in the bedroom) with all their own stuff: water spray bottle, substrate supply, feeding tongs...etc. There is a bottle of hand sanitizer in every section of the apartment as well.
I try to work with the established snakes first, but if I have to deal with the QT ones before the others (such as on feeding days since the QT snakes eat PK rats and the others are still on mice) I will wash thoroughly with soap then with the sanitizer, and will change shirts if I handled anyone, before going to the other room.

Currently, since I was given my newest snake while my het albinos are still in QT in the office, I have another QT tub in the living room to keep everyone separate.