by Seth Godin
1. Expecting gratitude in exchange for having done something that was hard. Yes, you built a company, you might even have bootstrapped it. Yes, you've got the machinery and the packaging and the retail space. Yes, you've navigated hiring people and yes, you finally shipped. I couldn't care less. I'm not going to buy your brownie/consulting/services just because you worked hard on it.
2. Spending money as a substitute for doing something great. Spending on marketing an average product isn't working anymore. You're far better off spending money on making your product better. A lot better.
3. Not realizing that it's your company, and your marketing better be as good as everything else. It doesn't matter if you don't like marketing or don't think you're good at it. Figure it out or go home. Sooner or later, you succeed because you were able to spread your ideas. So go to school and figure out how it works.
4. Listening to other people. If they're so smart, why aren't they running your company? Don't take a poll. Don't ask your mother-in-law, that's for sure. Cover your downsides, double your desire to take a risk and then just do it.
5. Failure to measure. All this is worthless if you don't test and measure relentlessly. Do what works. Kill what doesn't.