I firmly believe buying an office chair should be taken just as seriously as buying a car. Think about it: in your life, you will probably spend far more time sitting in your office chair then you will in your car.
Here are the three things you should do before buying a new office chair:
1. Sit in it. You have no idea how many people don't do this. Can you adjust it to an appropriate height so your knees are at a 90 degree angle and your feet are flat on the floor? When you sit comfortably, does your back feel supported? Remember, your chair should make it easy to sit with perfect posture.
2. Feel the fabric. Even check out the "ingredients" tag to find out the exact blend of materials. If you are buying an upholstered office chair, the fabric should be breathable and easily cleanable. Remember, you'll be sitting in this thing for hours on end, so pleather is never a good idea.
3. Take a spin. If you are buying a swivel chair, make sure it's loose enough that you can easily turn left to right, but not so loose that you are working hard to sit in one place. Some chairs allow you to adjust this feature, so if you're concerned, look for that too.
Before you buy any chair, be sure to ask about the return policy. Ask if you can return it if you don't like it — even if you have used it. It can be tough to know if the chair is the perfect fit until you have a chance to sit in it for a full day, so you want to be sure you can get your money back if it's a dud. Always keep those receipts!
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May want to post an ergonomics chair adjustment guide. I find most people have no idea what the proper posture and chair adjustment is, and then will either blame the chair, or buy accessories like foot rests or wrist rests or moitor risers to compensate, when the chair just needs to be adjusted properly.
www.Humanscale.com has a pretty good ergonomics primer.
I read an article a few years back on a group of Scottish researchers and their quest to find the least stressful sitting position. The standard back straight up, thighs parallel to the floor, feet flat on the floor was one of the worst positions for the body. Using a functional MRI scanner, they discovered that the thigh to body angle of 135 degrees (fully supported) with the feet on an angle footrest presented the least amount of stress. Just something to think about.
If you look at the Stressless Chair, which is not a desk chair, you'll see that it matches the Scottish findings. I have had them for decades, bought after a bad bike accident. Many of the ugly recliners folks love come pretty close to those specs.
When it comes to office chairs, the other key thing is "buy the best you can afford." This doesn't mean that it has to be the most famous - but you do need to read up about what counts and then test it. It should have arms and their height should be adjustable.
In addition to the chair, almost everyone has their keyboard at the wrong height, on a table or desk - and has them tilted up instead of down. Read SimpleHuman's site. I have their keyboard tray at work.
Where is the desk in the photo from?