Once the fleece is off the sheep it needs to be skirted. Many fleece sellers will do this for you, but you might want to do some in addition, depending on your definition of clean.

1. Spread the fleece out on a relatively clean surface.
2. Pick out all vegetation, poo, and any other sections that are too dirty or matted to spin (if you don't want to spin it, take it out now). Extra benefit: all that lanolin in the wool is great for your hands.

Buying fleece from 'coated' sheep makes this task much easier and, I think, worth the extra money you spend for the fleece.

People do this in different ways. Some will put the whole fleece in very hot water in a large tub - bathtubs work well if no one needs to shower. Other folks will pull out sections of wool. Although it can take several days (months?), I prefer to wash in sections:

1. Run hot water into a dish tub or sink. Add a smidge (3-7-ish drops) of grease-cutting liquid dish soap.
2. Pull off a section of wool about the size of a dinner plate or small platter.
3. Place this section in a mesh bag (lingerie bags are super for this), keeping the wool as spread-out as possible. Using a mesh bag helps keep the wool from agitating and makes transfer from one bath to the next much easier.
4. Place bag of wool on the surface of the sudsy washing water. Let it sink into the tub in its own sweet time. Do not smoosh, poke, squeeze or tickle the wool at any time (heat, water, and agitation will felt the wool, which makes it almost impossible to spin).
5. After awhile (30 min. to 2-ish hours), remove mesh bag and let it drain. Do not smoosh, poke, squeeze or tickle the wool at any time. It doesn't need to dry, just drain enough so most of the icky water isn't carried into the next bath.

Repeat these 5 steps until the used wash water is clear and no sediment remains in your tub or sink. It may take a few sessions. Do not smoosh, poke, squeeze or tickle the wool at any time. 

1. Run hot water into a dish tub or sink. Add a small gollub (teaspoon-ish) of white vinegar.This will cut any remaining soap and put the wool closer to its preferred pH level (on the acidic side).
   
2. Place mesh bag of wool on the surface of the clear vinegar water. Let it sink into the tub in its own sweet time. Do not smoosh, poke, squeeze or tickle the wool at any time.
3. After awhile (15 to 30-ish minutes), remove mesh bag and let it drain. Do not smoosh, poke, squeeze or tickle the wool at any time.
   
4. Run another tub of hot water without soap or vinegar. Rinse bag of wool again to get rid of the vinegar smell.
5. Drain. This time, you do want the wool to dry.

Repeat these 5 steps until the used wash water is clear and doesn't smell like vinegar. It may take a few sessions, and... Do not smoosh, poke, squeeze or tickle the wool at any time. 

Let your wool air-dry by placing it in an open area, free of birds, cats, squirrels, and other assorted critters. It may take a day or two, depending on air circulation.

If patience is not your forte, however, there are tricks:

• swing the mesh bag around in a big circle (outside) to fling out extra water, being careful not to twist the bag, or even better...
• put the mesh bag of wool into a salad spinner and spin, making centrifical force work for you.
  

After flinging or spinning out excess water, you still need to let the wool air dry. Wool can hold up to 30% of its weight in water but still feel dry.

• take the wool out of the mesh bag and place in a dry, warm place.
• use a drying surface that allows for a lot of air circulation (sweater/lingerie drying racks work well).