Recreational players often say they have a difficult time practicing their serves because they don’t have access to a tennis court or own a basket of balls. You can solve this problem with some chalk and one tennis ball.
Go to a hitting wall, or even a fence, and draw a line (the net) three feet above the ground (a regulation tennis net is three feet at the center strap and six inches taller at the net post). Then draw a circle, three feet in diameter, above the net line, with the bottom of the circle touching the line. Finally, take 13 steps from the wall (roughly 39 feet, half the full length of a court) and serve into the circle. If the ball lands inside the circle, you’ve hit a successful serve. Now maybe you can train your dog to fetch the ball for you!