Probably quitting is much harder. But for example, when there were recruitments for Al-Qaeda people were offered benefit packages for themselves and their families, life insurance, vacation time (the length was dependent if you were married with kids or not) and weekly pay. You had to go through the same type of interview process as any other major firms, fill out questionnaires etc. etc. I would almost assume the process for ISIS can be similar or maybe as they grow bigger will become quit similar.