The secret to keeping frizz at bay involves a few products: a leave-in conditioner, a deep conditioner and a styling product involving silicone. If you have curly hair, these should be staples in your bathroom cabinet. All either keep the hair moisturized or protects the cuticle from moisture.
Preventing frizz is basically a four-step process: deep condition once a week. Apply a leave-in conditioner to ends after a shower. When styling hair, apply a serum that contains silicone (look for "dimethicone" on the bottle) to wet hair, coating every curl.