It depends on the kind of tea, but generally I'll have green and pretty light black teas straight, and I'll put a little cream and sugar or honey and lemon in most other teas. My favorite tea is probably Lapsang Souchong, which I take with cream and just enough sugar to keep it from being bitter.
For iced tea:
7 generic (like lipton) teabags in 4 cups of water
microwave 6 minutes
pour into gallon pitcher
stir in 1 1/3 cups sugar until dissolved
fill pitcher with cold water
Pretty much 90% of what I drank while growing up was iced tea, and that's the way we used to make it. As a bonus, you can make a sort of pseudo Thai iced tea by not adding water, and just pouring the concentrate into a cup over ice with a little heavy cream.