It seems like people here have different tastes than people I know personally. Most people I've talked to aren't big fans of flavored teas. We generally agree that these teas always smell better than they taste. And to me, the taste is kind of a cross between black tea and herbal tea. It seems like it can't decide which one it is and the combination usually doesn't work that well for my tastebuds. I almost always have to sweeten it to make it taste better to me. The one main exception is chai tea because some rather strongly flavored spices are typically used in it. (And Earl Grey, I suppose, but that's commonly classified as black.) But if a lot of people suggest flavored teas, there's certainly no harm in giving them a try. I just wanted to provide a different opinion, sticking to regular teas. I grew up with regular old black tea, sweetened and with milk. Over time, I dropped the additions, almost never using milk and only using sugar when I feel the tea needs sweetening.
Do you have a preference for the black or green end of the spectrum? I find that black teas generally have stronger flavors than greens. I would think that for blacks, you could use almost any common variety, say Ceylon, Assam, Keemun, English Breakfast, Irish Breakfast, Earl Grey, etc., possibly steeping it for a little less time than normal to lighten the flavor a bit, and add some sugar or honey to help sweeten it up to your daughter's tastes. You can add milk, too, if you like, just try not to add so much that you start masking the taste of the tea. Oolongs are usually pretty nice, being basically in between blacks and greens. I'm not very familiar with them, but they usually have a nice taste. I believe the tea served in Chinese restaurants is normally an oolong tea. Greens tend to be lighter flavored, as I noted, but also tend to be kind of grassy since they're not processed much. Some people like that, others, not so much. White teas are practically unprocessed and of the couple I've tried, they had rather light flavors, but were pretty good. I think the first one I tried was White Peony and it was very nice; it actually had more flavor than I was expecting because I had heard that the flavors of white teas are usually subtle. I would guess that the white end is about as light as you can get, almost making flavored water.
I think the main tips, regardless of the tea you choose, are things other said -- steep/brew the tea for a bit less time than usual to help lighten up the flavor, and add sugar, milk, honey, lemon to help bring it more to your duaghter's taste. As she gets used to it, you can start easing off the additions. I wouldn't really recommend additions for non-black teas, from what I've read those types are all supposed to be drunk straight, but I suppose you can do whatever you like.
P.S. -- Herbals aren't strictly teas, but they can make nice drinks, like chris says. They're a completely different class, but some fruit herbal could be good if your daughter likes fruits and juices.