How about a Red Hat Society meeting at a local tea room?
Or you could have a bling party. Wear your favorites and bring some lonely jewelry to swap.
Informal parties are easier to arrange. Set aside one area of the house for your guests, like the kitchen nook. Ordinary table decor will work with mix-and-match china. Just add one or two holiday accents and some Christmas music in the background.
Are you hosting a Christmas tea for confirmed tea party lovers? Make it a recipe potluck. Ask each guest to bring 2 or 3 favorite tea party treats with copies of their recipes. Arrange to have both savories and sweets to avoid sugar overload.
Do you want help decorating the tree? Try a round robin. Participants can offer a different green tea and treat at each house. Include an ornament swap at the beginning to stimulate your creativity.
If you want to give take-home favors, keep it as simple as some green tea samples and a Christmas cookie tied together in fabric with a cheerful ribbon.