Allow your chive plants to grow undisturbed in spring until they are at least 6 inches tall. Clip back the leaves on half the plant with a horizontal cut to only 2 inches tall with herb scissors, leaving the other half at 6 inches.
Leave the chives to grow for two to three weeks for the cut half to reach about 4 inches tall. Cut the over-6-inch tall leaves to 2 inches tall on the second half of the plant (the side that wasn't cut before).
Continue to alternate cutting the sides down to only 2 inches tall through the growing season to prevent flowers from forming and keep new leaves tender rather than tough.
Watch for the base of your chive plants to broaden over the growing season as continued cutting will encourage new bulblets to form. As the plant widens, incorporate the new leaves into your alternating harvests.