You have the sofa. You have the chairs, the TV, the lamps. The last big piece for the living/family room is likely to be the coffee table. Finding a table can be a significant challenge. How do you know what size, height and shape?

Chicago interior designer Mitchell Putlack offered some clues.

Know thyself. Know how you are going to sit at the coffee table, Putlack says.

"Are you going to sit on a sofa or chair and put your feet up" on the table? If so, look for an ottoman-style coffee table and put trays atop it to hold food and drinks. Make sure it's at seat height so your legs and feet are comfy.

"Are you going to sit on the floor and eat off the coffee table?" If so, look for one that you can slide your legs and feet under.

The 18-inch rule. Putlack almost always recommends placing the coffee table 18 inches from the sofa or chairs. "Anything more puts the table too far from the people sitting on the sofa," he says.

Knowing this rule can help determine shape.

A small, round table could be perfect for a small space, Putlack says. A square table "becomes appropriate when you have a sofa and a couple of chairs on each side (of the sofa) or when you've got a sectional sofa" with both sections being the same length. The square shape could give you an 18-inch distance to all seating pieces.

Two's company. Sometimes, two smaller tables work better than one - for instance, if you have a "narrow space and a really long sofa," says Putlack.

The long and short and width of it. "The length of the table should always be long enough for everyone seated on the sofa to be able to reach the table without getting up from their seat," Putlack says.

The people/fret factor. Consider "who's going to be using the table and what they're going to be using it for," Putlack says. If it's kids with crayons or homework or adults without coasters, choose a hard material such as a stone or laminate. Or choose one that's "already got imperfections."

Karen Klages writes for the Chicago Tribune.