Wool cleans itself more than you would think (sample note). Air a jumper overnight by an open window after you wear it, and it is usually fresh again.
When it does need washing, use a wool cycle at 30 °C or wash it by hand, roll it in a towel and dry it flat away from the radiator.
Store knits folded, never on a hanger, with a cedar block in the drawer. In spring, put them away clean: moths prefer worn wool.