I recommend checking out the podcast
Writing Excuses. It's run by four professional writers, and really, most of what I know comes from that podcast. There are over 10 seasons, chances are there's an episode that at least touches on a subject you want to know more about. The podcast does focus on fantasy and sci-fi, but a lot of it is applicable to other genres.
There are two major way to go about writing. One is to create an outline for a story and then follow it. The second is to make it up as you go along, and of course, there are lots of people who fit somewhere in between the two extremes. For instance, some people may come up with major plot points they know are going to happen and then fill in the blanks while writing. It may be worth experimenting and trying out different ways to see which ones work better for you.
When coming up with a story, one way to look at it is to break it down into three components: characters, plot, and setting. I'd say character is most important though I'm sure you can argue for the other two. The reason I think character is more important is because if you don't have interesting people we can root for, why are we going to read a whole story about them? Of course, don't skimp on any of the three elements.
On the question of whom you are writing for, thinking about the audience can be helpful. If you have no particular audience in mind however, think about what interests you. The ideas we're most excited about tend to be the ones we can write the best stories about. And if you like an idea, chances are there are other people out there who'll like it too.
I usually focus on the speed of writing so I tend to skip on the revising step and just do all the changes one can in the editing part. It really depends on each individual and how they want to go about it. I'd usually almost never edit right after I'm done writing. That's because my mind would miss typos when it's still fresh. So I give it some time before I return to it to edit and publish.
Same for the most part. In fact, this chart is the first time I've seen editing and revising as different steps. It's usually just write and then edit. However, the way this chart breaks it down does help to illustrate that the revision process shouldn't just be correcting grammar and typos. You should also look at things like the plot. Is it flowing as well as it should? Is the pacing too slow? If so, what can you do to fix it?