If a grip is too big or too small this can cause strain or fatigue on the hand and arm. To properly fit a Badminton grip to your hand the general rule is to have one fingers width of space between the palm and the tip of the ring finger.
Do not forget to replace worn out grips with fresh grip, or put an over grip on for optimal comfort and control, this will prevent slipping and provide size to the grip for more comfort.
The first step to court domination is equipping Badminton gear that matches your style and level of play.