Rule: Transparency is key.
"Whether you're running a business alone or with partners, it's important to be open and honest with everything you do. If you're going to be a little late in paying your manufacturer, let them know. If you need an advance on your paycheck because you've got some personal stuff to handle, say something to your partner. All company owners should have open access to the books at all times. I experienced this firsthand when some bad stuff went down with a former business partner. In retrospect, it was my fault too because I didn't put my foot down with having access to the information, and because of that it gave an avenue for dishonesty. Transparency is paramount in running a successful business."