Tight curls will puff out when you comb or brush the hair which separates the individual hairs from each other.  To prevent that you need to keep the hair grouped together to form the curls.  Using soemthing to help the curls hang toether is sometimes necessary.  Some people will use an oil like jojoba or olive oil on their hair right after washing.  Comb thru the hair with a wide toothed comb after applying the oil and let the hair air dry.  Another option is aloe vera gel.  This will hold the curls more than the oil.  There are other hair products out there as well that will help to define the curls. 

I'm sure one of our curly-headed gals can add more suggestions.