Wool doesn’t need washing very often because it’s naturally stain and odour-resistant. Usually, hanging the garment outside to air is all that’s required. you can spot clean to target soiled areas, but don't scrub.
If you do need to wash however, use a wool-approved soap. Even baby shampoo is safe for washing wool because, like human hair, wool is primarily composed of keratin protein. Don't use laundry detergent as it's too harsh.
Follow these steps for best practice:
Place your garment into a container of lukewarm soapy water and squish and squeeze gently to saturate the fibres.
Let it soak for 5 or 10 minutes.
Rinse with cool water until the rinse water runs clear.
Gently remove, bearing the weight of heavy items.
Squeeze out smaller items in a rolled towel; larger garments can be carefully spun in the machine. Do not wring or twist.
Reshape whilst damp.
Dry away from strong heat sources. That includes tumble dryers!