How do you feel comfortable with a group you know (too) well; and create rapport with a group you don’t (or barely) know (without making it all about ‘you’)?
These strategies might be interesting to explore:
(1) Be really clear about your role as facilitator (see above points about building confidence and contracting). If you are facilitating a group that you know well (potentially your colleagues, partners, peers, etc.) make sure they know what to expect and what not to expect from you as you put on your facilitator hat, as your contribution to the meeting will be quite different to how you would otherwise.