Disclaimers- do they really protect the proffesional?

Was wondering whether disclaimers have any legal weight? Say for example I wanted to get into private practice but didnt want to be registered with any association and i were to get my clients to signe a disclaimer stating that i was not responsible for things outside of my proffesional practice, would this cover me? Or would such a disclaimer be useless in a court of law if I were to be sued for what ever strange reason?

Thank you for your time!