I moved your topic to 'Planning' under the industry forum, as this is what your question pertains to.
As for success with tea rooms, tea rooms like any other business can be fickle. I can't say from personal experience, as I've never owned a tearoom, but just seeing some people in the industry, I find that a lot of people open it not because they're passionate about tea, food, or entertaining, but they 'think it would be fun'. They go to trade shows, buy awful quality tea, buy lots of overpriced china or whatever, and bake scones from a box. Of course, it can be fun and it should be, but you should really have a passion behind your planning. And be sure you can put your all into your planning- if you're really doing this as a part time gig or for the 'fun' factor, simply have more tea parties with your friends.
I can only advise that you go to trade shows, ask for advice from sales representatives- get a feel to who just wants to sell you tea, and who will actually talk to you about stuff you want to offer in your tea room, goals you have, what kind of atmosphere, etc. Visit tea rooms in your area, get a feel of what you want to offer and what kind of experience you want to make for your guests. Try out and become masterful on the subject of tea- simply knowing Earl Grey is different from English Breakfast doesn't cut it. And really, really try to be different.
Also, put your ego in check. I've heard stories of tea room owners who could not get over themselves and had to have everything their way and would not sway to the guests. Guests won't be impressed and will not visit again. Guests will however come again if the service is excellent, the staff is knowledgable, the offerings are varied, and the tea is a fine and high quality selection.
Being opened on Sundays also help.