All the obvious ones have been mentioned already, so I’ll just add:
Keyboard tray if your desk doesn’t have one. It allows you to achieve the 90 degree arm position without having to set your desk too low or your chair too high.
Wrist pad. A nice gel pad provides great support for your wrist. Just make sure your keyboard and mouse are at the appropriate heights, because if not, a wrist pad can make it worse.
Head rest add-on to your chair if it doesn’t have one.
Laptop stand to lift your laptop screen to eye level. It also helps to keep it aligned to an external monitor so they are the same heights.
All the obvious ones have been mentioned already, so I’ll just add:
Keyboard tray if your desk doesn’t have one. It allows you to achieve the 90 degree arm position without having to set your desk too low or your chair too high.
Wrist pad. A nice gel pad provides great support for your wrist. Just make sure your keyboard and mouse are at the appropriate heights, because if not, a wrist pad can make it worse.
Head rest add-on to your chair if it doesn’t have one.
Laptop stand to lift your laptop screen to eye level. It also helps to keep it aligned to an external monitor so they are the same heights.