Lots of people have mentioned having passion. Passion is for hobbies, sports watching, and family it does not put a penny in your pocket. Passion leads to tunnel vision. The goal is to make a living and usually a great living. If thing seem even a little off. Slow up or even stop. Find out why. You should be your own hardest critic. Do not go the other way and be a perfectionist to the point of excess, spend money without a gain for you or your customers. There is a balance.
Read as many books as possible on successful and failed ventures and related material! so much to learn and helps keep up the motivation.
This is a brief list of my favorites so far: (please share yours!)
The intelligent entrepreneur
The Lean Startup
Grit the passion for success
This is going to sound very weird. But ask her to meditate at least 20 mins a day. When you reduce the chatter of your conscious mind, your mighty subconscious has the opportunity to present you with ideas, information and problem solving. It comes in form of 'Aha!' moments.
Also there will be times when she will panic. When things won't work. But as she learns to quiet her mind and go within, there will emerge a surreal sense of 'Knowing'. With experience of course.
Not to forget health benefits like blood pressure. Not the advice you were expecting I'm sure. :)
Never give up , expect the worst, hope for the best