First make sure you have some quality tea AND water. It's good to use spring or filtered water for the freshest taste possible. You'll also want to get your proportions right, typically one teaspoon of loose leaf (or one tea bag) to one cup of water. Then choose your brewing method:
Hot Brewing is the quickest. Using a ceramic bowl or pitcher, put in the amount of tea you want and add half the amount of boiling water (so for 2 teaspoons of tea you would add one cup of water). This will make a sort of concentrate. After letting the tea steep for 5 minutes, add cold water to the mixture using the same amount as you did hot water (in this case one cup of cold water). This will dilute the concentrate. You can then serve over ice, and save the rest in the refrigerator.
Sun Brewing takes about six hours but is well worth it. Put tea leaves or bags in a glass jar, then add cold water and cover with a lid. Set outside in a sunny location for six hours. When it's done, serve it over ice and store the rest in the refrigerator.
Cold Brewing is also a great way to get delicious flavor from your tea leaves. Using a pitcher or large jar, use the standard proportions of tea to water for the amount of tea you'd like to make. Let it sit in the refrigerator for eight to twelve hours or overnight, then serve it over ice.