The inception of a new venture is picking a problem / user need that you’re passionate about. After that, I’d suggest thinking on how you have an unfair advantage over others around this problem – do you have a lot of industry experience? Have the problem yourself? Have access to a wide, relevant network?
When you cleared the above two areas, I believe it’s incredibly important to think about where you will operate from a strategic standpoint – your industry / market.
It’s a common startup saying that the most successful companies did not disrupt a market, they created an entirely new one. Despite being a very good way to force yourself to see competition in a more expansive way, the needs of consumers don’t change as often as people think – they just hire different products to solve the same needs.
Given the above, I’ve been thinking of markets in a spectrum, using speed and dynamism as its unit of difference. Here’s a quick idea of what I mean:

I’m sure there are tons of other options, all of which are useful in picking an area of focus for your new venture.
When you do, you’re ready to start talking to other people to validate your assumptions, but that’s for another blog post 🙂