If you want to be successful in any venture it's important to lose your inhibitions. I don't mean you have to run down the street naked, in full view of the neighbours, but simply this - stand up for yourself, and have more confidence. Which is another way of saying - believe in your skills.
There, believe in your self, your skills and experience. You are good at what you do. You can write. And you can write persuasively. There are lots of successful freelancers, entrepreneurs and businesses out there doing what you want to do. They started in the same way, with hard work and application.
Oh yes, you need to work hard and apply yourself. Don't think success (whatever that means to you) is just going to come knocking at your door. It doesn't know where you live yet. So the first thing you have to do is tell it. Compose a letter. Get some business cards. Set up a website. Do what you need to do to tell success you are waiting for a call. Then it will come looking for you.
I live and work in England. The English are naturally guarded (and I don't just mean by the sea). We err on the side of caution. Reserved is a word commonly applied to us. We generally don't like to brag, but sometimes we need to get our message out there in forceful terms, which can look like bragging. But it's not. If it's done persuasively, honestly and to the right people.