There are many ways to protect yourself and your clients. Pro photographer Stephan Bollinger covers 3. Insurance, releases and non-disclosure agreements. If you haven't thought of how you need to protect yourself before, it's never too late.
Stephan Bollinger says:
Later down the track, when the hobby slowly turned into a job, I had to painfully learn that most of the images I produced over the years could not be used commercially, simply because I never asked anyone to sign a release form. Looking back, I wish someone would have given me a few hints in this regard, and I shall do just this with this post.