In most cases, a study is a room destined for reading, doing paperwork or computer work. In certain particular situations, it can also function as a room where the children do their groundwork or from where one runs his/her home-based business.
For example, if the space shall be mainly meant for reading, try a wall-to-wall wooden bookshelf packed with the latest (or oldest) editions of your chosen literature. Buy an ottoman or another type of couch, some plush chairs and a tiny end table to can put your tea and tray of cookies. If, on the other hand, your activity will be based on computer work, go for a modern desk, computer couch and all the excellent gizmos you need. You should also try to arrange for storage space, whether in the form of cabinets or other filing devices.
Don’t ignore to think about lamps. If you have a couple of large windows, one pretty lamp and a wall membrane fixture should be more than enough. However, if natural light comes hard to find, you should consider buying more light sources, so as to never put your eyes in danger. Drapes are also very important and tend to impact the volume of light and heat that comes into the room, so choose knowledgeably.