ClientA currently pays me 10K (about 25% of my salary) a year to write technical industry articles, press releases, etc. I have never signed a contract or agreement with ClientA. I have recently been approached by ClientB, a competitor of ClientA in the same industry, to also write technical case studies and press releases. ClientB could amount to at least another 15K a year or more. I have a good relationship with ClientA and would like to inform them about the offer from ClientB. However, I think that ClientA will not want me to write for any competitor. On the other hand, ClientB has informed me that they will permit me to write for competitors as long as I sign a non-disclosure agreement. Should I stay with ClientA at 10K a year, or do I accept the offer of ClientB, which could be a potential for more money but a risk of losing ClientA? Is agreeing to write exclusively for one client in an industry a smart thing to do? It could cost me a lot of potential work in that industry. I've only been freelancing for 3 years and I need some advice!
I do not recommend locking yourself into a situation where you only write for one client per industry. Think about it - ad agencies may have a dozen clients in one industry with no problems. What they do have is confidentialty clauses in their contracts with each client.
I suggest you discuss the situation with Client A - let him know you have been approached by a competitor and it would mean a significant amount of business for you. You do not have to disclose the identity of Client B - in fact, I would discourage you from doing so. Tell Client A you would like to accept the assignment from Client B, but do not feel comfortable doing so until there is a confidentiality agreement in place between you and Client A. If Client A is a realistic business person, he/she will appreciate your honesty and your willingness to take steps to protect your existing relationship.
Best of luck to you.