here is what I have learned in three years of my "startup" and six years of another company.
- Selling/Trading skills are more important than your product
- Customer relations are most important. If internet is banned tomorrow I can sell toilet paper to my customers
- Mediocre product and superb selling skills is better than superb product and no selling skills at all
- Finding a sweet spot for your product price takes time and adjustments, selling cheap is a road to fiasco
- Acting quick on market changes is not always a good idea, probably isn't good idea at all
- If you are partner in a company, when money comes rolling in - problems start, make sure you all have the same goal
- customers do not know what they want in most cases, you have to bring them your vision and sell it to them. Do not expect them to tell you what they want and that would be your feature list, it won't
- last, but probably most important. Focus on one area and do it good. I don't mean necessarily on one product, because selling one and only thing is a lot harder than having a leverage of several things to offer - but if you sell several things, be sure they are related to one area.
edit:
one more thing. this is one thing, if I could tell only one thing, that I would say what I have learned. No matter what other people are saying, advices you read/get, it doesn't matter at all to you and your business until you learn it on your own and pay for it in time and money, the hard way. So listen to others only as a general guideline of what to expect, but you have to learn what is best for you on your own, sadly.