Summarize this article in one sentence.
Beginner tennis players often serve the ball using all of their speed and strength. You don't need to hit the ball with all your might, though! Don’t put 100% of your energy into a serve. Professional players tend to give about 80% energy. When you serve, focus more on accuracy than power. Practice hitting the ball exactly where you want it to go rather than just hitting is as hard as you can. Concentrate on your aim. Carve out time in your tennis routine to work on practice serves. By putting your weight on your back leg, you’ll set yourself up to create momentum going forward. This will make it so your body moves in a much more fluid and natural way when you take your shot. Even though this sounds easy, every tennis player must master this skill. Train your eyes on the ball when your opponent serves it to you. Make it the focus of your entire vision. Follow it as it comes to you. Watch as you hit it with your racket. Then, continue to follow the ball as it moves across the court.  Keep your head still and your eyes on the ball even when it makes contact with your racquet. It's natural to want to look ahead at your target, but you have to break this habit.  Remind yourself during every practice to do this and it will eventually become second nature. Don’t rush your shots. Use as much time as you can to serve, position yourself, and to gather your thoughts between points. If you rush yourself unnecessarily, you’ll break your focus and take shots that are inaccurate. Avoid putting a death grip on your racket. This will not only tire your hand out quickly, but it’ll probably take you longer to respond to your opponent’s shot. Instead, hold the racket loosely and gently. While this may take some getting used to, you’ll be able to improve your power and accuracy. Some people restring their racquets themselves, but  unless you have a tennis stringing machine and a few special tools, it's better to hire a professional to do it. Once you do, you’ll likely see some improvements in your hits. This is especially true if you feel as if you don’t have a hard enough serve. Look up tennis shops or sporting goods stores in your area, and call to find out if they do restringing. Many of them do.

Summary:
Focus on accuracy, not speed, when serving the ball. Put all your weight on your back leg before you take a shot. Keep your eyes on the ball at all times. Move slowly and deliberately on the court. Hold your racket gently, if your swing is rigid or slow. Restring your racquet if your swing becomes weak or inaccurate.