I have my new Filly strop on the way in the mail. I'm new to straight shaving, and I don't understand how people cut their strops. I know you strop the razor spine first. So, how to newbies end up cutting their strops? I have been using my belt until it gets in the mail, and I haven't managed any cuts yet. I want to know the common cause, so I can avoid it when my new strop comes. Is it carelessness or the razor slipping?