Setting Up Shop
Your desk may well be the most important part of your workspace. It not only serves to support tasks, it also holds your above (phone, computer monitor) and below the surface (CPU holder, keyboard tray) equipment. The layout and the height of your work surfaces are crucial to best posture and work efficiency. The right ergonomic setup is the one that helps you work with the greatest efficiency and with best possible posture. This depends in part upon the type of work surface you use.
Steady Footrest
A fixed-height desk, for instance, may have a center drawer that prevents the installation of a keyboard and mouse tray. In such a case, you may need to adjust the height of your office chair so that your keyboard can be placed on your desktop. This is not a perfect solution and it would be better to get a new desk that enables you to use a proper keyboard tray. If this is impossible at present, make sure you have a steady footrest to support your feet as you work.
If your work surface has a fixed height, it is likely at 28"-30" above floor level. This may be ideal for writing papers, but it's just too high for comfortable mouse and keyboard work. If possible, you should install a keyboard/mouse tray system underneath your work surface. This should be height-adjustable. Or resort to placing your keyboard and mouse on your desktop and raise the level of your chair. Add a footrest to make sure you're posture-perfect.
Cable Access
If you are lucky enough to have a height-adjustable work surface, make sure it's at a height that is comfortable for writing. You can then attach a keyboard/mouse tray system that is similarly height-adjustable, to get everything at just the right height.
The positioning of your desk is also an important point for the ergonomic office desk. If at all possible, make sure you have space on each side of your desk. This should ensure ease of access to all of the cables used to connect your computer.
To test your workspace for ease of viewing, sit at your desk, and pull in close to your work surface. Direct your eyes straight ahead. What is now within your view is called your "optimal viewing zone." Anything that you need to see during your work hours, such as your screen, source material, and etc., should be within or close to this area.
Next, check that you can reach everything you use with frequency during your work hours. Place your arms out at the side and bring them in until your hands meet at the front of your body. The semi-circle you just outlined is termed the "normal reach zone." You shouldn't have to bend, twist, or stretch to get to the thing you often use during work hours.
Last of all, check your working area. Allow your upper arms to rest against the sides of your body. Use your elbows to swing out your forearms at your sides and then bring them in front of you until your hands touch. The area included by this sweep of your forearms is called the "normal working area." Anything that you must operate with your hands, for instance your mouse and keyboard, should be situated within this area for perfect efficiency and comfort.