It seems that all my author friends who have blogs are currently writing about the craft of writing. Therefore, I must also put in my two cents' worth (or with inflation, maybe my twenty-five cents' worth) on this topic.
In my brief writing foray, I have found that it is best to begin with those things I know and with which I am familiar. I don't write about daily life in Greenland two centuries ago, because I don't have a clue about what happened. One can obtain a reasonable amount of correct information through research, but a new writer needs to concentrate on the details of description, characterization, and plot before branching out into the world of research.
And let's get those grammatical conventions out of the way. Writers simply cannot slink by without them: spelling, capitalization, sentence structure, punctuation, diction--all those pesky little details that go unnoticed unless done poorly.
Therefore, in my grand total of two books (one published and one awaiting publication), I have based my stories upon actual events and real people. It's quite simple to make a character believable when that character is a real person whom I know. Appearance, personality traits, mannerisms, speech patterns--are already built in. And, making a scene or a chapter ring true when I was "there" is fairly easy as well. I can (and did) use license to change the time frame and details to make the writing flow, but 95% of what I've written in my two books actually happened.
I'll leave the more difficult details of writing to the seasoned writers--but if you are just starting out as I did a few years ago, write as often as possible about what you know, then go back and polish it, several times if need be. In high school writing, my students often create that first draft--and then turn it in as holy writ to be graded. They resist having to revise and aren't interested in changing one iota. However, in polished writing, the difference between a high school single-draft essay and mature writing style comes in the form of hard work--lots of it.
Revising and rewriting are not very glamorous (I mean, who goes around saying, "Oh, I can't wait to revise those ten pages I wrote yesterday!"), but they can pay big dividends in polishing an otherwise drab piece. Sometimes, I set it aside and go back to it a couple of hours or even days later. With fresh eyes, the words sometimes come tumbling out so quickly that I must speed type to capture them.
Try it. You'll like it--or at least improve your writing skills.
I have even revised this short post several times over the course of this day. And, I will most likely revise it several more times before I'm satisfied with it.