Olive green is a shade found in nature, a cool colour that evokes a feeling of warmth and comfort. In Asian tradition, green signifies hope and vitality. It evokes feelings of harmony. Olive green is considered a muted shade of green, most at home in a comfortable, relaxed colour scheme. How you decide to decorate a room with olive green walls will depend upon the design style you're aiming for.
If you'd like to create a contemporary space -- a room with colours that shout out for attention -- introduce a colour that is complementary to olive green. Complementary colours are found directly opposite each other on a colour wheel. For olive green, maroon is the complementary colour you would introduce to set the stage for a bold contemporary room. A sofa covered in maroon fabric, an area rug with maroon running through the design, lampshades with maroon accents and wall art with splashes of maroon would send a loud and clear contemporary message.
Another option when aiming for a contemporary room is to use a split-complementary colour scheme. You do this by allowing the olive green walls to be a backdrop to the two colours found directly next to the complementary colour of maroon on the colour wheel, eggplant and rust. For example, if the walls of your bedroom are olive green, you might layer the bed with eggplant coloured bedding and rust coloured throw pillows. You could introduce the deep purple of eggplant through a flower arrangement on the nightstand and work rust and eggplant in through dramatic artwork. Rust coloured window treatments would pull the entire look together.
For a more traditional decor, consider going the analogous route with your colour scheme. You accomplish this by pairing the olive green walls with one or both of the colours found on either side of it on the colour wheel. Mustard yellow and midnight blue are analogous to olive green and both work to create harmony in a room. This is because olive green has something in common with both of these shades. Olive green and mustard yellow both have yellow at their base, while olive green and midnight blue share blue as their base colour. If the walls of your kitchen are olive green, you could cover the table with a mustard yellow tablecloth and display a decorative mustard yellow dishtowel in a conspicuous place. Use midnight blue dinnerware and display midnight blue coffee cups on a cup rack for true visual impact. A midnight blue rug in front of the sink and mustard yellow window curtains would take full advantage of how well these colours work together.
If you're more into modern decor, the monochromatic work can add serenity and drama to a room at the same time. You create a monochromatic look by layering in varying shades of the same colour into a room. For example, if the walls of your family room are olive green, you might have furniture covered in mint green fabric and hang grass green drapes. Incorporate a variety of greens into the space through scatter pillows, throws, artwork and area rugs. Once you've layered the different shades of green into the room, you give it a punch of another colour. A red vase in the centre of the coffee table will give you that modern edge.