If your second serve is a cream puff, here's an alternative.
I’ve always been confused as to why recreational players who struggle so much with their second serves don’t try something different. Whether it’s mental or technical, they donate games’ worth of points by tossing in double faults and sitting ducks. I think if you can’t get the job done with the standard serving motion, you should consider experimenting with an underhand topspindrive serve. While unconventional, it’s totally legal, and if done properly it’s effective and reliable.
To try it, hold the racquet with your regular forehand grip. Set up with your weight loaded on your back leg. Drop the ball out of your tossing hand and take a vigorous low-to-high swing while transferring your weight forward. It’s like feeding a ball in practice, only you hit it with more conviction, direction, and spin. Make sure you get plenty of shoulder turn to provide momentum and use your legs to explode into the shot. The more racquet acceleration you have, the more spin and action you’ll get on the ball.
You should be able to direct the shot to any part of the service box (particularly your opponent’s weaker side) and the topspin will kick the ball up, making it difficult to attack. If you prefer, start a few feet behind the baseline to allow for a step forward with your front foot. This will also leave you balanced and in position for the return.
If you’re stuck with a powder-puff second serve, you’ll be amazed at the confidence that you’ll get from starting a point this way. Don’t be surprised if someday soon somebody on TV is using this serve.