I really struggled with blogging at first. I felt really awkward and worried that readers would be negatively judging my writing ability.
My confidence in my writing grew through academic writing that I do for university. As I've mentioned, I'm working towards a BA in English Literature, so I write a lot of essays for my course. I find academic writing a bit easier in a way. It's formal in tone and you can't inject your own opinions into it. It's nice to sit back and hide behind the learned persona. A person could read my essays and have no clue about me at all, which is kind of the point. But writing in that way feels safer. You're not vulnerable. I receive good marks for my essays and my lecturers always comment on my clear and fluent writing style. Having that sort of feedback on my writing itself has been a huge confidence booster.
Blogging, on the other hand, is the opposite of academic writing. It's highly personal and you are putting yourself way out there. Anyone who reads this can know all sorts of things about me that I've put into the narrative. It's also more informal in style, more conversational. I feel that the way I write here is fairly representative of the way I talk: full of contractions, colloquialisms, and slang.
Having the positive feedback from an unbiased source (my uni lecturers) has given me the confidence to write in other ways too, including here on the blog. I think it's taken me a long time to be confident in my writing and putting it out there for the world to read, but I'm feeling much better about it now.
The other thing that's helped me is reading. I've always read a lot, and I'll read pretty much anything but the biggest tip I can give is to read authors whose writing styles you want to emulate. If you want to learn a fast-paced, aggressive, informal style, read Stephen King. If you want a more refined, contemporary, literary style, read some contemporary literature: I recently read Burial Rites by Hannah Kent and really enjoyed her writing (and the story). If you want to write something set in Victorian times, read Mary Shelley. Or better yet, read all of them and use each author's strengths to develop your own style.