Before you buy an office chair, check to see if the backrests, seat, and armrests are adjustable. You should be able to adjust the seat height and tilt of your office chair to your own preferences, and ideally the seat should be comfortable enough to support you comfortably, while letting your body breathe. The most important feature to look for is good lumbar support, as an office chair with a good lumbar support lets your back stay in a position that is good for its spine health.
Before you buy a coffee table you should ask some yourself how you want the table to function. While a coffee table often ends up being the focal point in a room, it does have other functions than simply looking good. Also, since there is a great variety in materials, you should pick one that best fits your needs. For instance, you most likely don not want a glass coffee table when you have toddlers. You would not want an easily destructible surface or finish either. Before you buy your coffee table, you also have to pick shape and size.