You can limit coupons by shipping method, payment method, product combination, and even customer role. A coupon that only gives a $5 discount if the customer spends $50 or more, for instance, can be created automatically.
Coupons are great but don’t use them too often. People might think that everything you sell isn’t worth as much if it’s always on sale. Discounts can be planned around anniversaries, birthdays, holidays, and special events for customers.