There's no need to vacuum too often. You can pick up lint by hand! I use a special brush for rugs to keep them clean... If there's a stain, clean with lukewarm water (putting a cloth underneath) and it will come out easily. If the stain is persistent, diluted Marseille soap or black soap are perfect! 
For stubborn stains, use sparkling water and rub gently with a clean sponge. Leave for 30 minutes or so, then sprinkle the stains with baking soda and, when the powder is completely dry, vacuum up. Baking soda is a good natural product for cleaning wool carpets, so don't hesitate to use this method for stubborn stains.
As a last resort, if the stain is heavily colored, such as coffee, chocolate, wine or curry, Vanish or carpet spray will work! (But not eco-friendly). Avoid detergents.

Dry well underneath, using a hair dryer if necessary! 
Your terrace or balcony is ideal.
The rug must be completely dry before it can be placed in your home.
A badly dried wool carpet could quickly become a moth's nest and give off a bad smell.
From time to time, if you can't beat or shake your carpet, it's a good idea to turn it over for a few days to air it out and shake off any residual dust.
And in summer, if you can expose it to the sun once in a while, it'll do it a world of good!