Measure the room where you will use the rug. Create a drawing of the room on graph paper. Include furniture in your drawing. You don’t need to get too elaborate. Just sketch the footprint, or basic size, of each furniture piece.
Research information about rugs. Rugs come in basic sizes like 8x10 feet which are pretty easy to find. They also come in round, rectangle and square. Visit a few carpet and rug stores to understand the approximate size you want. Consider using carpet remnants as well. You can get the exact size you need and have the edges bound for a fraction of the cost of a rug.
Move the furniture that will sit on the rug out of the way. Use low tack painter’s tape to tape the outline of the size rug you are considering. Move the furniture back; it does not need to be all the way on top of the rug. Stand back and look at the space.
Consider how else you will use the rug. You may need space on the rug for kids to play or a dog to lounge. Make sure the rug will be big enough to accommodate all of the activities that normally occur in that room of your home. You want the rug to be big enough to be practical without overwhelming the space.
Start shopping. Take your time. You don’t want to come home with the first rug you see. Develop a relationship with a local carpet or rug retailer. He will notify you when new items are available when rugs you are interested in go on sale.