How to be a tennis professional ?

An above average hand & eye co-ordination skills,leg speed,strong shoulders
If you have all that start hitting the ball against the wall

Also grunt when you hit the ball

get someone to pay you

Well, I might put the tennis professional goal out of your mind. But getting better is great goal to have.
I had a short career as a professional athlete and here's a tip, from a famous coach, that makes a lot of sense.
[i]Practice doesn't make perfect. Only perfect practice makes perfect. [/i]
What he's saying is you need to practice with intention. It's not just hitting balls. At first, it's going to be about form and balance. You can't worry where the ball's going. Once you establish a solid technique then you can start working on skills like accuracy and ball speed. Tennis is like a lot of sports. It's about muscle memory. So train your body with the right techniques at the beginning and you'll be able to repeat them as you continue playing.
Most anything athletic is going to be hard at first. Failure is part of it. So embrace the failure and keep going because, if you do, you WILL get better.
Have fun with it.

Have fun with it. The pros tend to start earlier in life and have thousands of hours in by the time they are your age.

As with anything, practice makes perfect. I was AWFUL at tennis when I first picked up a racquet. Now I fancy myself against friends who have played tennis far longer than I have.

It is a game best learned from childhood. Developing your technique and understanding how to play it properly takes years.

Keep at it! The more practice, the better you'll get.

personal coaching is key to establish good form and not develop bad habits