The first step to being able to play the Maracas correctly is to learn how to properly hold them. This is typically done supporting the maracas with your thumb behind the instrument and the first three fingers on the front, leaving the pinky finger up in the air.
In this video, you will see how to correctly hold your Maracas.
This next video shows you with more detail how to hold the Maracas. The three fingers (index, middle, and ring) are positioned linearly from top to bottom.