One of the chapters in Rework is titled "Say no by default." The leading quote in that chapter is by Henry Ford, "If I'd listened to customers, I'd have given them a faster horse."

I agree saying no to your customers or to your boss or even to friends and family is underrated. Okay, no may be overused by negative people or it may be overused by literal technical people. But, yes is being overused by too many people to get the business, to please the boss, keep family and friends happy.

I was asked to make an SEO proposal for a business. My proposal emphasized getting current website traffic stats, communicating with the client about their products, figuring out how their customers searched for their product and setting new goals for website traffic. Their immediate and only question back to me was "how may keywords will you give us?" Their mindset was that they were buying keywords, not trying to improve their website traffic. I knew I couldn't make them happy. I suggested that they should go elsewhere. It was a smart move for me. I didn't get paid, but I don't have the stress or an unhappy customer to deal with.

I say no a lot when people ask me for a very specific software feature. I ask them to tell me what problem are they trying to solve. Working from the problem and working together to come up with the solution has always made a better product. I imagine use riding fast horses with engines today, if Henry Ford didn't ignore the solutions from his customers and concentrate on the problem.

Saying no to the boss isn't a bad thing either. This can be a whole other post, but this no is frequently about priority clarification. Boss, "Can you do X for me?" You, "Yes, but A is also due by then. Which is the priority?"

My bottom line is to think before you say yes or no. Get more information if you need it. Ask questions to clarify. Start a conversation and think about what is most important.