One of the very first things that you have to decide about when redesigning a room is the rug or the carpet. Quite obviously, it is one of the first things that you will have to put inside your room--even before your furniture--so you'll have to think well about this.
A rug can radically change the look and feel of your room. It can add character and hide the faults of your floor, or totally put your room into those groups of rooms that are far from being inviting. They can be there to help you emphasize a certain furniure, or maybe for just practical purposes. Whatever your purpose is, planning is still needed because rugs/carpets can be quite expensive depending on the material and quality of the rug.
Basically, there are three first characteristics that a buyer has to worry about, namely, the size, shape, and color of the rug. The effects of a little variation within the three criteria can have a large effect on the atmosphere of your room. For example, a large rug in an equally large room can evoke a certain sense of formality while in the room, while circular rugs can soften the atmosphere and perhaps even cheer people up. Using bright colors for your rug is also recommended for children's rooms.
Patterns is also an important characteristic that you will have to look at. Plain-looking rugs are often seen to be boring and too formal, so if you want to give life to your room, choosing rugs that have graphics in it may be the way to go. They also happen to be less sensitive to dirt (the dirt is deemphasized), so that also means less maintenance for you.
Finally, you also have to take a look at both the weave and texture of the carpet. I won't elaborate much on this, but you can read this article and take a look at some weave types.
Whatever your choice is, I do hope that you get the desired effect. Carpet shops are all over the metro so you certainly won't miss out on picking a very good design for your room.