How to welcome and greet volunteers.

Greet them with enthusiastic energy! It's contagious!
Show them where they put their personal stuff in a safe place.
Gently communicate to them we need them to stay to the end of their shift and we are counting on them.
Hand them off to their team 'Lead' and the lead will get them oriented.

Notes:

If we have too many volunteers, can ask some to go for walk or take break for an hour or so till we are in need of them.
If we have too little volunteers, ask current volunteers if they can stay later to help us fill out that need.