Make sure that you've spoken with your facilitator to confirm any special needs or details and let any employees / associates know that you'll be holding a class so they're aware of the offering / avoid double booking. Other tips to remember are:
Provide wifi password to facilitator, if necessary
Ensure the lights are on and AC / Heat is appropriate for group
Let the teacher and students know where the restroom is located
If food or beverages are available, let the teacher know details & deals
