As a cabinetmaker, I've often been called upon to build computer desks and other work spaces.Most of what's been said here is excellent information for a work from home computer station. I would add only a couple thoughts.
First is the seating. Be sure that you have a chair with sufficient adjustability. That means up-and-down, seatback angle and seat bottom tilt/angle. Sit in this and adjust until you are totally comfortable. Then, grab a book and read while sitting for an hour or 2. If your back feels good, you got it right. if not, readjust.
Second, once you get the chair height right, set the work surface itself to the right height. Be sure the way you use your mouse doesn't put your wrist at an unusual angle and that your use of the keyboard allows for proper wrist angles. Carpal tunnel is no fun!
Be certain your monitor is placed at the right distance away to allow your eyes to focus properly on the screen. Be sure your glasses do not require you to strain your neck to see the screen properly. IMHO, if you wear bifocals like me,it's a good idea to have a pair of glasses that optimize the amount of lens you see your screen through, ie "computer glasses".
Be sure to check for lamp glare or other distracting sources of light such as a sunny window.
FYI, if your office work is secure in nature, consider an Ethernet rather than wireless connection. Don't trip over the cords!