I have to admit, as I'm writing, I don't necessarily notice when I've improved. I'm a firm believer in the 'the more you write, the better you write' adage, and I'm certain my writing is better with each short story and novel I complete, but up until now, I'd be hard-pressed to tell you where I had improved other than finishing.
Stuck in the midst of my "quick" round of editing, originally just cutting lines and making changes based on in-manuscript notes I left to myself (now essentialy rereading the whole thing), I am beginning to notice improvements, at least in terms of my awareness of what does and does not work. I think it may be in the editing stage that a writer can see where their strengths and weakessnesses lie, and where they improved. Your story may be better written than an earlier one, but you'll be able to see that when you begin to edit.
For example, lately, I have been starting a lot of sentences and questions with "So..." in my real life/talking to friends online. In text, that habit is more clearer apparent, so when I see it in the novel, I know there's a problem and it needs to go. I'm not adverse to starting a sentence with "And" or "But," but it needs to make sense, address the previous sentence and sound "right" enough to be its own sentence. (If that makes sense.) Basically, it needs to add to the story, and starting a sentence with "So," IMO, doesn't.
I've also noticed a tendency I have in my story-writing to repeat words or phrases as a point of emphasis. I love it. It sounds great in my head. Or Character B will sarcastically repeat what Character A said. As I edit, I try to read the story as Random Reader #1 (in hopes to have many more than 1 in the future). I've been asking myself, "Would this throw me out of the story?" "Would I skip over this?" and I find that those repetitions (especially the quoting someone else in dialogue, which looks a bit awkward with the "'double' quotation marks") tend to do that to RR#1. Thus, I cut and reprase if necessary.
Likewise: just, that, really, actually, very... etc.
Words that I like to use, and feel are needed for emphasis when I write them down, but in editing, I cut most of these. I think I might keep a few "just"s, and I'm working on toning down the "a bit"s, "at least"s and "seemingly"s.
I realize these are a small part of editing, but when I stopped to think about it, I rarely took out the numerous counts of "just" in my early stories. In the past, I didn't use "So" very much (at the start of a sentence), but I'm sure there were other "real life" verbal ticks that made their way into my writing to its detriment.
I like to think this is a tangible/visual point for me to see -that- I have improved, and where I improved, at least in one respect.
So that's my small revelation for the day.
Happy writing, everyone,