Q. Is there any halachic principle about how to make money in business?
The Talmud says, “When a person is led in for judgment in the next world, the first question will be, ‘Were your business dealings honourable?'” (Shabbat 31a). If this means that you will make less profit, halachah would say, “So be it.” If this means that your competitor will become a megamillionaire before you, again halachah would say, “So let him.” Not that making a profit is reprehensible, but it should be a profit with “clean hands and a pure heart” (Psalm 24).
Businesses succeed and fail, business people rise and fall, but those whose business practices are ethical will not have to try to talk themselves out of God’s day of judgment.