I always find myself saying this: you can add anything to tea. Anything. It is all a matter of taste.
Just remember that, whatever you add, it should enhance
the flavor of your tea, not hide it.
Additives I have found that work best include: sugar, honey, vanilla, milk, pepper, lemon juice, and cinnamon.
In general, black teas take additives better than other teas. A good earl grey stands up well to milk & sugar. A good assam can stand up to almost anything.
If you are used to drinking things with tons of sugar in them, you probably aren't going to be happy cutting it out completely.
If you are used to drinking coffee, I would suggest starting with 8 ounces of a good, smooth earl grey or assam. You can also start with a chai (Adagio calls their chai "oriental spice"). Avoid over-brewing, as this will make it taste bitter. Put a small amount of sugar (either half of what you were using earlier, or 2 tsp max, whichever is less), and a small amount of milk. Drink that for two weeks (unless it doesn't taste sweet enough, in which case keep going until it does). Then halve the sugar again. Once you get down to a half teaspoon of sugar, wait two weeks, and then start branching into other teas without adding any sugar at all. You can work backwards from blacks to oolongs to greens to whites; or you can just pick one that sounds good. Whatever you like.
Another route is to drink a sweet fruity tisane (herbal tea), such as blood orange or wild strawberry. These are usually so sweet that they really don't require sugar. And Adagio's chamomile is perfect with only a half teaspoon of sugar (otherwise, the taste is a little cloudy).
You might prefer a jasmine oolong, such as Jasmine #12. It is light, crisp, and sweet. And I find that you can make it pretty strong by adding extra pearls. You might find that you like it without sugar.
And yet another route is to start with a really light tea. The lightest tea you can find (for example, buy a white tea and brew 1 tsp/cup for 4 minutes at a 170 degrees F). Then, pretend it is water. Warm water, but water nonetheless. After a while, a month or so, it won't taste like water anymore. And you will find that your taste buds are accustomed to lighter flavors, and that you enjoy other teas more.
A few additional notes:
1. Water quality is essential. You start with crappy water, you get crappy tea. Find a water that tastes good to you. If your tap water isn't very good (like most tap water), use spring water, or mineral water, or a 3-stage water filter (PUR makes one). Just don't use distilled water.
2. Make sure you are using a large non-steel basket-style filter. Basket filters allow the teas to expand more, imparting more flavor. And steel can impart an unpleasant taste. Recommened personal-size filters include the ingenuiTEA
by Adagio, and the Yoyo
by Bodum. The latter can be purchased on-line or at your local Target.
For groups, you can either get a tea pot with a glass or gold basket filter, or you can get a tea pot that doesn't have a filter (just a strainer in the spout). I am sure others here could recommend one if you are interested.
3. If a tea is bitter, brew it for less time. If a tea is weak, you can either brew it longer or add more leaves (depending on whether or not brewing it longer makes it bitter). How long you brew any particular tea is a matter of taste. So don't feel like you're doing something wrong if you are adding extra tea leaves, or brewing it longer, or even brewing it shorter.
P.S. If you find a tea you genuinely don't like the flavor of, there is no shame in that. Most tea lovers have a few teas they don't like. Just try a different one.
P.P.S. Good luck!