The only requirement to work on these farms is that you are a member of WWOOF. Membership is 250 CZK a year, or 350 CZK for a couple. Once you become a member you then get a list of farms. The type of work you do and for how long, along with the length of stay all depends on your agreement with the farmer. For short stays the organization recommends bringing your own sleeping bag. For longer stays they suggest something more could be arranged. They also recommend that you bring personal; items such as a towel and tooth brush.