I consider myself to be a good writer. In fact, I know I am. I didn't get that way by accident though and neither did my nephew. I've been a heavy reader all my life and even though some of my ability as a writer is innate, it was encouraged and it flourished from a young age because I was encouraged to read.
Reading is what taught me to spell and it taught me to construct a coherent sentence. I didn't learn those things as lessons so much as I absorbed them by reading correctly spelled and well edited fiction, non-fiction and periodicals. At 48, I'm a heavy reader and accordingly, I become a better writer the more I read. The more I read the more I write and the two things continue to reinforce each other just as they always have.
People, newbies to the blog world usually, ask me all the time how they can write better. My flippant answer is always "read more, just make sure it's not useless self-help or business writing." Seriously though, a jargon-filled seven minutes will change your life or whatever won't do the trick. Read literature, classical literature particularly. But maybe that's just me voicing my unwavering support of the Canon of Western Lit.
Barring a deep dive into Herman Melville, there are tools available to help anybody be a better writer.
First, buy a style guide. It doesn't matter if it's the AP Stylebook (my favorite), the Chicago Manual of Style, Strunk and White's Elements of Style, The MLA Style Manual or any other one. Settle on a style and use it consistently.
Develop empathy for your audience. By that I mean work on your ability to take a step back from something you've written and put yourself into the shoes of a stranger reading it for the first time. Are your points clear? Are you asking your audience to logical leaps without any kind of guidance? Is your use of pronouns consistent and are those pronouns' antecedents easy to identify? The first person to see something written is the person who wrote it and you can learn to edit yourself.
Check to make sure you're not plagiarizing. I tend to absorb a lot of what I read and sometimes, ideas and whole phrases fly off my fingers and they're not mine. It's happened plenty of times over the years that I've used a clever turn of phrase only to have it pointed out later as someone else's signature phrase.
Plagiarism isn't always lifting an entire article from Wikipedia, sometimes it's more subtle. Subtle or not, it's always unacceptable. Reread your writing or use a plagiarism checker.
Beware spell checkers because they're not always right. Written English is a morass of illogical spellings and there are as many rules as there are exceptions to those rules. Familiarize yourself with the most common
exceptions and commit them to memory. That's always a work in progress by the way. I still can't spell commit or commitment consistently.
Writing comes easily for me, it's something I can do as readily as I can think or breathe. But so far as I'm concerned it's always a work in progress --it's something I'm forever striving to improve. Whatever your skill level, your writing will always improve if you read and if you practice writing.