As requested, here are my basic steps for washing clay (extracting wild clay from soil).
Other people might do things differently, using cheese cloth, or spreading their clay on a board to dry.
This is what I do so I can get away with just using some buckets and water.
First step: Find some clay soil to dig up and take home with you. If it hasn't rained recently, you're probably going to find that the soil is very hard, so bring a good shovel and wear your boots.