A disclaimer or liability waiver is NOT foolproof or bullet proof--it reduces the odds of being sued, but does not provide absolute protection, since it really only protects against "negligent," or accidental/careless, harm you do, and not "grossly negligent" (more than ordinarily careless; so bad we can't believe anyone would act that way) or intentional acts. And, of course, it only protects against those who sign it. Set up an LLC; the LLC will protect you from most (but not all--no protection is perfect) business related liability. Then have clients/customer execute waivers for additional protection.