I want to develop the sensitivity of my hands/arms particularly for tennis. I feel this is essential to get more controlled spins.
How can I develop sensitity of hands/arms?
Specificity of Exercise:
If you want to get more controlled spins in tennis, practice hitting lots of tennis balls with topspin and backspin.
When your goal is acquiring a certain skill, training with specificity of exercise will get you closer to your goal faster than doing different types of unrelated exercise. Repetition will give you the sensitivity of touch that you need.
Swimmers develop sensitivity in their hands so they can hold water more effectively, by using the feel of water pressure to determine the pitch of their hand. Three tips I have seen are:
Doing these activities just before your serve could make you more aware of sensations in your fingers so you can better learn from them.
Sensitivity has different factors all of which I am not even aware of. I have listed some below. In circus, you may have seen glass ball performing such as here which definitely requires good focus and hand manouvering, perhaps useful for tennis player.
Warming up also the small muscles handling the small weights
Gym training with small weights such as 1kg and 2kg.
Better relaxation such as cold paths.
Playing with smaller balls and balls of different weights
Better hand-eye-coordination