The ratio
Per gallon: 6 family-size tea bags (Luzianne or Lipton), 1 to 1.25 cups of plain white sugar, 1/4 teaspoon of baking soda. The baking soda neutralizes tannins and is the difference between great sweet tea and bitter sweet tea.
Method
Boil 4 cups of water. Drop tea bags and baking soda into the boiling water, remove from heat, cover, steep 15 minutes. Pour the concentrated tea over the sugar in a gallon pitcher and stir until dissolved. Top with cold water to one gallon. Refrigerate at least 2 hours before serving.
The garnishes
Lemon if you want it. Mint if you grew it. Never bottled syrup — once it's brewed, it's brewed.