This is a follow up, to my post on how to become a great returner. Most recreational players are enamored with the speed of fast serves. And I'll agree, it's fun to swing away on the first serve. But in terms of importance, it's consistency, placement and then power. Keep it in this order. Because you can't have a good serve without consistency.
I equate consistency with topspin. When you hit with topspin you are adding safety to your shot. With this in mind, it makes sense that the topspin serve would be the ideal choice for the second serve right? That means it's really important to get this serve down. If you're struggling with getting it in, here's a useful exercise that will help your consistency. I do this all the time.
Place a hopper several feet away from you. Grab a few tennis balls and practice throwing them into the hopper, while using the topspin service motion. This simulates the motion of the serve and familiarizes your muscle memory with that motion. Once you're able to get the ball in consistently, stand back a few more feet and work at getting it in from further away. You can also do this same exercise on the tennis court, just stand inside the service line when you're throwing the ball. Do you notice, tossing the ball from a close distance requires a lot of arm action but as you back up you start to turn through the toss? This is because the rotation of your hips adds extra power to your serve. When you are ready to add power to your second serve, you can accelerate through the striking part of the service motion, while turning through the ball.
Now let's talk about the flat and slice serves. These are best used on the first serve. Your goal with them, will be to establish control of a rally. There are several ways to do this. One way, is to serve a hard ball to your opponent and hope for a short reply. Another way, is to angle the serve away from them and look for a weak return. Which puts you in the attacking position. Since these two serves are offensive. Think about where your opponent's weakness is. Most players have a weaker backhand than forehand. If you're not sure which side is weaker, play a few rallies and see if your opponents starts to hit the ball short. If they give weak replies off of a certain stroke, that's the key to target that side when serving.
Another important aspect to serving, is to have a consistent toss. I like to put the ball right on the palm of my hand and then practice tossing it straight up in the same exact spot. The more consistent your toss the more successful your serve will become.
Anyway, try out some of these tips and let me know how it goes.