It still amazes me to see players being taught to just get the serve in.
Having the mindset to "just serve in" is a BIG mistake.
For one thing, the less specific you are, the more likely you are to make a mistake.
So with serving, you want to be specific to where you are trying to serve the ball.
ALWAYS have a plan when you serve.
NEVER just toss the ball up and try to hit the ball over the net.
So, always have a specific focus every time you serve.
Here are examples of specific things you could focus on when you serve...
Placing the ball to specific area of the court (zone 6)
Create a solid contact through the center of the ball
Creating a floating action on the ball
Forcing a specific player to pass the ball by aiming your serve to them
If you just pick one of these things to focus on, this strategy is a lot better than just trying to serve the ball in.
The following drill creates a competition between the server and the passer.