I meet a lot of people at various stages of experience as online entrepreneurs, and there seems to be a common ingredient in those who are not doing very well. It's not lack of knowledge. It's not having poor computer skills. It's not being technophobic. It's not having poor people skills. It's not even "analysis paralysis" - although I think it is akin to this.
It's being unsure of themselves.
More to the point, it's the paralysis that being unsure causes. We often see the admonishment to "just take action." And I agree with that advice wholeheartedly. But it's doubly tough for those afflicted with an unwarranted level of self-doubt.
That's why I say fake it til you make it. Another way to look at it is to think of this as a self-fulfilling prophecy. Act as though you're sure something will work. Just adopting this mindset - even if you secretly still harbor personal doubts - will sometimes produce magic.
And trust me, once you have that first taste of seeing something you were unsure about work for you, you won't have to fake it any longer. It's all about pretending to yourself that what you want to try will work simply because you're trying it. That "fake" confidence will become the real deal.
And now here comes the really hard part of this: not letting failures do the opposite to you. If something does fail when you try this, force yourself to ignore the failure part and only focus on what new skills/knowledge you picked up during the process of acting on it in the first place. That's so key here. Be a 'silver lining' person, even if it goes against your basic nature - as is usually the case with people who are self-doubters.
What you'll find is that over time you'll become more confident and you'll be able to focus on the silver linings - even in the inevitable failures. Just don't let being unsure of yourself stop you from starting. Fake that part of it until you don't have to anymore.