The main way to make sure that your furniture works well together is to ensure that there is a common 'theme' running through each and every item that is in a particular space. The theme can be color, texture, style, period of construction or something entirely different.
A vital element when decorating your living room with a contemporary theme is your wall treatments. For this design style the colors can make or break the look - consider adding shades of browns and black or a sharp black and white look to the room. Try using a neutral color paint on the walls, or if you want something different go with a leather or suede wall covering.
Similarly, the right ottoman can be used as a foot rest, storage unit and coffee table. Decorating your living room space should be a fun experience.