Here you will find some generally accepted guidelines for selecting an area rug that will fit your space well and perfectly accent your living area but do keep in mind that personal preferences should trump any type of rules put forth by the rug industry or interior designers.
Oriental carpets were originally woven and tufted by hand to cover the ground or floors in tents and buildings with earth or stone floors. They added warmth and color to the lives of those living in these dwellings. European castles and lesser homes often had earth or stone floors covered with things like rushes or straw and when travellers brought back rugs from the East those who could afford them bought these carpets to enhance their homes as well. Settlers coming to America brought rugs with them or the knowledge to make them. Soft woven or tufted flooring covers are used around the world to add comfort color and style to homes and commercial spaces.
Rug placement most probably is one of the factors that you might want to consider first in selecting a rug. It is important to know where the rug is going to be placed. As you consider the placement of the rug the other factors will follow: such as color materials and size.