I really think that a lot of the things you suggested actually come down to relationships- just because you "hold the rights" are you going to sue someone over $500 if they use it without permission? Are you really going to require contracts over those first projects where a client is trying out your services? I had aspirations of using a lot of these ideas when I started but ultimately I realized at the end of the day... the only thing that keeps my clients paying is our mutual trust. I would really struggle to ask for money up front and I think that it will really change the nature of my relationship with my clients.