What would you tell to prospective clients to let them comfortable sharing confidential information (like source code) with you, specially when beginning a new employment relationship?
When I faced that problem once, I couldn't come up with more than an NDA suggestion.
My basic advice from practicing architecture is to consider behaviors indicating a lack of trust a red flag when talking to <i>potential</i> clients.<p>At best, it's a sign that the <i>potential</i> client is out of their depth in terms of experience dealing with professional services. That is to say that <i>good</i> potential clients for professional services tend to have used similar services before. Potential clients with unrealistic expectations who become actual clients make their unrealistic expectations your problem.<p>At worst, and perhaps more typically, people tend to project their character onto other people. People with less inhibition to not pay/deliver tend to act as if I am going to rip them off. A person who fundamentally views business as the process of extracting as much as possible from everyone is going to approach me as if I held the same view of misaligned interests.<p>After many years I developed a simple test. I require a retainer paid upfront and applied against <i>final</i> invoice. Logically, a willingness to write checks to me is a premise of the agreement for services. The ability to write a non-bouncing check for my services is also part of the deal. And a <i>potential</i> client who balks at writing a check upfront indicates a lack of trust that over the long haul may not be worth trying to overcome.<p>Good luck.