Be aware of the pressure required to press the keys to engage the switches. Mechanical and membrane switches have different feels and feedback mechanisms. Be aware of the differences and select the style that enables you to use a lighter touch. Select a pointing device that meets your needs. A trackball moves more efficiently, but is more difficult to use for precise, controlled movements.
Trackballs utilize more hand movements than a mouse.
Avoid using your thumb to move your mouse. Select a pointing device that fits the 'size and shape of your hand. Use light tapping movements to depress the buttons on your pointing device. Avoid excessive force. Determine which adjustments are necessary for your work environment and match the tray to your needs.