This is a mixture of all ingredients actually. There are more teas out there than any one person could ever possibly explore. A cold alcoholic infusion creates a very different profile from the sorts of flavors you get from tea with boiling water. It also provides a surprising punch of authentic flavor in drinks like "Long Island Iced Tea". Currently I am experimenting with a Black Apricot Tea, but for your first round unless you have something in the cupboard you really want to get rid of I suggest using a plain tea, just to get a feel for the flavor.
The tea infuses a very distinct tannin that is different from the woody tannins of cacao nibs and cinnamon. It is herbal and potentially more delicate. The Tea infuses into the alcohol very quickly, so you don't want to leave your infusion for more than a day, and quite honestly you may find a couple hours is all you need. The flavor takes to sweeteners, and all the traditional tea compliments. For inspiration I suggest wandering through the tea aisle at your local specialty shop. Tea blenders and marketers have been exploring the culinary possibilities of this ingredient since the beginning of time, and have a mass of possibilities that you can easily pick up and apply when blending infusions to make a custom liqueur.
Ratios: As with normal tea a little bit will do. A couple tablespoons will infuse a large mason jar quite nicely, though ratios will vary depending on the product you're using. Try to get large whole leave teas though, as you will draw out the bitter aspects of the finely ground teas used in bags very quickly and if you use a fine loose leaf tea you're likely to end up with sediment problems in your final product that you'll have to rack out. In terms of turbinado sugar or regular sugar that can easily go either way, or a pure green tea honey liqueur could be exceptionally nice. This one honestly could be an entire blog unto itself.