Use black tea. There's a reason it's black tea; any other tea just wouldn't work.
For the tea?
The thing about southern-style sweet tea is that it's a great way to drink bad tea. This is why most people use Lipton or Luzianne tea bags. I've used both, but always found it comes out better with Luzianne, and in fact most southern places that make it using Luzianne. I should say that I haven't made southern-style sweet tea in a long time because, as much as I love it, there's no coming back from good loose leaf tea. And using a high-quality tea to make southern-style sweet tea is very much missing the point (and, honestly, a crime against high-quality tea
).
If you're dead set on using loose leaf tea, I recommend finding a cheap loose black tea. The cheaper, the better. Get some tea bags you can use to put the black tea in. If you get tea bags that are only big enough for a cup, fill 12 (with about 3-4 tsps of the black tea for each bag). If you find some that are big enough to make a pitcher, fill 3 or 4 (with about 9-16 tsps of the black tea in each bag).
So here's how I do it. Keep in mind that this is from memory and using Luzianne tea bags, but the method will be the same with loose leaf tea as long as you use the bags...
Boil about 4 cups of water in a sauce pan. Remove it from the heat and steep the tea for 5-10 minutes. Remove the tea bags and discard.
Stir in 2 cups of sugar. Adjust this to your taste; less or more, depending on how sweet you want it.
And now, you have a choice:
If you can't wait, then pour it into a large pitcher over ice. Stir until it's cold and the ice has melted a bit, then enjoy.
If you can wait, pour what you have into a large pitcher (you should have way more pitcher than tea; a gallon pitcher is what I've used) and top off the tea with water (cold is fine; if you're using tap water, make sure you filter it unless you live somewhere with a reputation for really good tap water, like NYC) until the pitcher is full. Then leave in the fridge overnight.
Keep in mind that before the ice or water, the tea is
super concentrated and obviously (by virtue of steeping it so long in boiling water) a bit burnt. It will NOT taste good hot or without the ice melting in it or the extra water. That's why you use so much black tea in the first place (and why you don't want to use a high quality black tea). That said, the amount of tea you use is, obviously, adjustable to your tastes. If it's too strong, just use less tea. You can always test it by making a single cup...
If you do make a single cup, use one 1-cup tea bag filled with 4 tsps of the tea and 0.5 cup sugar. Pour into a glass over ice and stir while letting the ice melt. If it's too strong, use less tea; too sweet, less sugar. When you find the amount of black tea and sugar that works for you for one cup, simply multiply everything by 4 and go from there.
Like I said... I've not actually made it with loose leaf black tea before; I think I'll give it a try...
ETA: Yes, I realize this was last updated in February... I haven't been around in a long while and saw this and wanted to respond. Sue me!
) 
