Use a metal tape measure to measure the area where you want to place the corner sofa. Measure out from the corner in each direction to see how long a corner piece you can fit on each side.
Look around your room and take note of the color scheme where the corner sofa is going. This will help you to get a sofa that will fit your decor. You can even take a picture of the room with your digital camera to take with you when you go shopping.
Decide if you need the corner sofa to have any extra features. For example, some sofas are corner sleeper sofas, which you could use for visiting family. If you want to be able to recline, you can look for a corner sofa with recliners or with a chaise on one end.
Visit some local furniture stores to view their selections and be sure to look for sofas in colors and materials that complement your home decor.
Evaluate the size of the corner sofas that you see in the stores. Check the dimensions to make sure the one you favor will fit in your space and that it will seat enough people. Also look to see if the sofa is in one piece or more. It can be easier to work with and position or change positions of corner sofas that come in more than one piece.