It sounds like a simple question.If you’re running a small business, what’s the best way to spend your money? What percentage of your annual revenue should go to salaries, training, marketing, investing in new equipment, retirement savings?The answer, though, turns out to be unexpectedly complicated.Wouldn’t it be so convenient if there were handy rules of thumb? After all, we try to use them when we make choices about our household expenses — like the one that says your housing expenses shouldn’t be more than about 25 percent of your income.Yet looking closely at even that longstanding principle suggests why this
