Most poodle hair curls on its own to a certain degree. Some poodles however, such as red-, cream- and apricot-colored poodles, have a softer or looser curl to their fur coat. If your poodle is under a year of age, its fluffy hair may be due to puppyhood and could grow into full curls on their own. Otherwise you should try one option after another, by process of elimination, to see if they help your poodle's hair grow in curly.
Wait until your puppy is a mature adult dog before worrying too much about its coat. Puppy coats are typically sparser and fluffier than adult poodle coats.
Wash your adult poodle, then let its hair air-dry without brushing it out. This may help it to form a tighter curl on its own.
Try conditioning your dog's hair after washing and before letting it air-dry.
Make sure your poodle has an adequate, well-rounded diet. Check with your vet to make sure your pet has no nutritional deficiencies.
Keep your dog's fur well combed out so that it doesn't develop mats or tangles.