I wish there were a magic answer. If there is one, I don't know anyone who's found it yet. Most business owners tell me they rely on gut instinct to one degree or another. Gut instinct is that inner voice that tells you that it "feels right" to add another location,hire more employees or take on more debt.
I'm a big believer in trusting your instincts. But just like the famous Thomas Jefferson saying
"the harder I work, the more luck I seem to have," a similar idea goes for gut instincts. The more information you are armed with and the more planning you do, the better your gut instincts. That's why a financial person should be an indispensable member of your team, as I pointed out in "Expansion Plans" by Lena Basha in My Business magazine :
' ... one of the most important people on your growth team should be an accountant or financial adviser. "They can really help you understand your business from the inside out, which is necessary when projecting future cash flow that will help pay for the expansion expenses" .... '