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.
The sizes that are used for the living room are 4X6 feet and 6X9 feet. Larger living rooms should have more than one piece on the flooring. You can also use smaller ones to place by the fireplace preferably in front. In order to promote unity and harmony to the living room use similar colors and styles.
Whilst maintaining themes throughout your space make sure that you do not add too many and also that there are not too many dominant pieces in any given space. By their very nature the quality of a natural wood finish can be very alluring and eye-catching so avoid using tons of this material everywhere.