The rough reciepe I follow for 1 gallon, is 2-3 litres of fruit juice (pure fruit juice from the chilled cabinet), 800 - 1000g sugar, yeast nutrient, pectolase. Variations to that are 1 cup of strong tea and citric acid. NEVER top up to one gallon immediately, leave room for the fermentation, sometimes you'll get several inches of foam, you can top up once the initial vigour dies down.
I vary the sugar depending on the SG of the fruit juice and the final wine I want. Similar for the tanin and citric acid, certainly for summer drinking chilled wine I think it needs both the tanin and acid, not so much in the winter. Also depends on the type of fruit juice you use. We're a fan of Apple and Apple + Mango all year round but the flavour varies significantly between batches. You can always add dried tanin and acid after you've finished the fermentation to taste.