[altsyset]

This is great advice, I just want to add few things.

1. When ever you come up with an idea, write it down in a designated notebook,

2. Next make a list of why it would work and why it won't,

3. Study the pattern.

If you had made enough idea you will see how you think. You will find out if the self doubt is coming out of fear or a logical argument. Whatever the outcome, you would be in a better situation to take action. When you are ready to take action

4. Pick the idea that has highest market potential and suits your strength

5. Elaborate it into more detail by brainstorming and taking notes to strengthen you conviction.

6. Execute! Execute! Execute! Don't look back