Make at Least 50% of your First Serves Tennis Gator September 23, 2018 Singles Tactical Principles A first serve needs to be aggressive and fast but will not be very effective if it is not going in. To be really effective you need to make at least 50% of your first serves. Be aware of this and adjust accordingly while you play during a match. This post is only available to members. Please APPLY FOR ACCESS or LOG IN .