I don't know of pithy sayings, but something along the lines of "going through the proper channels" is deeply ingrained in a lot of people. Following that advice has meant I've passed up a lot of opportunities and allowed people to, however well meaning, say no to things I otherwise could have done. I'm somewhat of a believer in "It's better to ask forgiveness than permission," but like all advice, you really need to think through whether and how it applies to your situation.
One other note: "It might be better to do b2b first then try b2c." I've almost never seen people advise businesses try to tackle B2C, and I think it's just the allure of being a recognizable name that attracts people to that market.