First you document your idea. You should be comprehensive, but that doesn't mean you have to produce a doctoral thesis length plan. Rather you want to make sure you have touched all the different things that have to happen to succeed. Then, you evaluate your approach. The goal here isn't to figure out if your idea is good or bad, but rather to begin to figure out what are some of its weakest elements.

People who live in more than two countries are more successful innovators.

I find social media as fun and engaging as the next person, but imagine if all the creative talent that was pouring into finding increasingly clever ways for us to broadcast daily banality (and then serve ads based on what is learned) instead focused on some of the UN Millennium goals? The world would be a better place.

Think about how you will start and where you will go. Get the head with logic and the heart with visuals or stories. And think about your core customer and all the other stakeholders as well.

It's one of the underappreciated skills required by an innovator - they have to be able to convince lots of people to do things that might not be fully rational (invest in the company, join something that is likely to fail, try a product they've never seen before), and if you can't tell a good story it is just very hard to make that happen.

Most startup companies have two people, and they figure out creative ways to swarm problems. They move faster and have more impact.

Avoiding along some dimensions is easy. Create organization space and bring in some new talent so the innate cultural resistance is less material. Unfortunately, it's rarely that easy.