Tea with the Queen! Yes, if by queen you mean the Quinceanera girl because she is the queen for a day. This is a classy affair, pinkies up. For decorations use teacups, tea pots, lots of flowers, lace and pearls. I forgot to mention it in a picture but it be cute to add gloves to your outfit. Food for this occasion can be quite simple. Think finger foods, petite sandwiches, biscuits, crumpets even and plenty of desserts.
For this theme I chose a Champagne/Blush very pastel colored dress and paired it with brighter bolder colors like yellow and wine red. You can do the same. You don't have to be so matchy-matchy. Don't limit yourself to just literal flowers either, try to use floral prints too, whether in dresses or in like tablecloths for example.
For favors give out something like stainless-steel Tea Infusers. If you want to get more specific with your tea party theme you can go the Alice in Wonderland route or easily do vintage.