A basil plant can produce up to 24 cups of leaves, according to the August 2007 edition of "Organic Gardening" magazine. To get the most yield from your plants, you need to prune them to encourage basil to branch out. Genovese basil is a common herb in Italian cooking, but there are varieties that complement Greek, Thai, Indian and Chinese cooking (among other cuisines), according to "Vegetable Gardening for Dummies" by Charlie Nardozzi. Basil even comes in flavors from lemon to licorice.
Pinch off the center stem after the plant has grown for 6 weeks from seed, to encourage it to branch out.
Prune the plant every 2 to 3 weeks by pinching off some of the upper leaf pairs, even if you don't need the leaves for cooking, to encourage the plant to grow bushy and produce new fresh leaves.
Harvest the upper leaves when you want to use them by pinching off the stem just above where a pair of lower leaves branches off. This will encourage the plant to branch out and grow more leaves at that point. Harvest as often as once a week.
Pinch off any stalks with flower buds when you see them developing, unless you want to save seed for planting next year. Preventing the plant from blooming encourages it to put more energy into producing leaves.