There are several ways to wrap a sari correctly, but a common method is to wrap it counter-clockwise around your body after tucking it into a matching petticoat, pin the tip of the sari to a matching blouse, and hold the remaining fabric in the crook of your arm. For a proper fit, make sure the blouse is close-fitting and the petticoat is not very flared.
To correctly wrap a sari in the traditional style, tuck one end of the sari into the petticoat, around your waist from right to left, with the lower end touching the floor. Make five or six pleats about 5 inches long, making sure they are even and turned to the left. Tuck the pleats into the petticoat, just to the left of your navel. Drape the remaining fabric around your body and over your left shoulder. Secure it to your blouse with a safety pin, if desired.
Alternatively, to wrap a sari the Bengali way, omit the pleats, and wrap the fabric over your left shoulder twice, securing it with a key bunch. In the Gujarati method, fold the pleats to face right instead of left, and drape the sari over the right shoulder. The Maharashtra way does not require a petticoat and instead uses a longer cut of fabric wrapped between the legs and around the waist. The Tamilian way is similar, except the sari is wrapped around the waist twice.