Matthew,
If this is not a project based Section 8 property, and it accepts and participates in the Housing Choice Voucher Program, you can contact the local Housing Authority that administers the vouchers for your participating residents. They can certainly guide through the process (it is not difficult or arduous.) As a courtesy to existing residents, the day you close the sale and take possession of the property, then you can notify the residents of the change in ownership/management. Those are just a couple of generic suggestions. Your attorney will advise you on leases obtained in the sale and how to handle that, as well as, any plans for continued/future tenancies.