Rule #1: Never let it get soaking wet!
You are lucky if you own a real wool rug. They're a gorgeous addition to a home, not to mention an environmentally friendly one. Wool is a natural renewable fibre that does not off-gas synthetic chemicals; it naturally deters bacteria and dust mites and lasts forever -- even generations, if cared for properly.
But that care part can be tricky. Some of the do's and don'ts of wool rug care might come as a surprise. For example, did you know you should never get a wool rug soaking wet? Wool is extremely difficult to dry once it gets wet. The bottom layers are hydrophilic, meaning they attract and retain water. But do not despair, for there are other, less watery ways of ensuring your rug stays clean.
Start with vacuuming, but don't get too enthusiastic. Too much vacuuming can pull fibres out of the rug, which isn't good. Rug Knots recommends vacuuming the top twice a month and the underside every two months. Never use a beater bar, nor a vacuum that is overly powerful. (Apparently Dyson is bad for this.)
"Protect the rug from the vacuum by placing a piece of nylon screen over the rug and weighting it down with books or bricks. Vacuum over the screen. Or tie a piece of nylon mesh over the vacuum attachment and change the mesh frequently as dirt accumulates."
Brush out pet hair. Vacuums often leave pet hair behind, so use a stiff brush to remove this from both sides of the rug. Brush always in the direction of the nap of the rug. A better rule is just to keep pets off any valuable wool rugs, if possible.
Spot clean. Tackle marks and stains individually, in order to minimize the area getting wet. Spot clean with a damp cloth, then be sure to blot thoroughly until the spot is bone dry. You can use an 8:1 ratio mixture of water and white vinegar to get rid of food stains, dirt, cosmetics, and modelling clay. Red wine spills require immediate action with salt.
Shake it or beat it. Rugs up to around 5'x7' can be taken outside and shaken. A half-minute of vigorous shaking will remove most of the dirt. Alternatively, hang it over a railing and beat with the flat side of a broom. It's a workout, but a satisfying one.
Clean it with snow. This is a curious old technique used in snowy regions of the world, and one my aunt swears by. On a day when the temperature will hold below freezing and there's at least 3 inches of snow on the ground, drag your area rug outside. Let it acclimatize for a half-hour, then pile it with fresh, clean snow. (The acclimatization is to ensure the snow doesn't melt into the wool.) Beat it around the rug with the flat side of a broom for several minutes. Flip it over and do the same on the bag, then shake off excess snow and leave it to hang on a railing for 30 minutes. From Apartment Therapy:
"The deep freeze kills smelly bacteria. Beating in the snow loosens dirt and grime. And sweeping the tiny snow crystals from the face of the rug removes any last particles from the surface. The result is a deodorized, bright and clean rug."
Rotate the rug. Don't let it sit in one spot forever, or else the colors and patterns will fade and certain portions will get more worn than others. Turn it in place, or put it in another area of your house.
Cushion it. Get a rug pad and keep that between the floor and the rug. Not only does it feel great on the feet, but it prevents the rug from wearing through as quickly.