Below are several epiphanies that I have had during my tiny, insignificant writing career that I hope will help you. I struggled and bashed myself unmercifully until there was light so that you don't have to.
(1) You should never stop writing because you think your writing is full of shit. The first draft of Beat Until Stiff was absolutely horrible. I had several people tell me this and they were right. It was AWFUL. Did I stop writing? No, I licked my wounds, and because I am rather a pugnacious and stubborn person, I said to myself, "Okay, make it better." And I did. The second draft was only sort of awful. I kept at it. Is it a great book? No. It's an okay book. It does what it set out to do, and I learned a hell of a lot about the process of writing from rewriting it, oh, say, six times. I re-wrote the first chapter 30 times. I am not making that up. And it took me five years to sell it. I was lucky, yes, and I happened to be in the right place at the right time (after going through wrong place and wrong time on numerous occasions).
(2) Keep writing. You'll get better. Half the game of writing is learning who you are as a writer. Your voice. How your brain works with the English language. This takes TIME. I mean years, not weeks, not months. So your first few attempts weren't great. Keep at it. Part of this process is voodoo. You keep on writing and gradually it will come to you that, hey, this is the way I put words together. It will feel like the shoe fits. That doesn't mean that you'll be able to write flawless prose, it just means that you now *know* what your characters are supposed to sound like. And when you've found your voice and then you can't find your voice for a specific idea, it is hell on earth.
(3) Learn basic grammar. Yeah, I mean this. Because a misplaced comma can change the ENTIRE mood of a piece, and, no, I can't be arsed to put up an example. But punctuation can make a BIG difference. And lack of it. Punctuation is the conductor of your words. It has the baton, and it gives your writing the beat. Trust me on this one. You'll find yourself debating comma choices before you know it. That doesn't mean that you let grammar strangle you. Some of it depends on your voice. I have a colloquial style and my current series is written in first person. I can get away with a lot of grammar no-nos because my narrative sounds like a person talking to you. It's one of the strengths of this series. Having said that, I need to watch it because I have a tendency to overdo it. Grammar really is the drumbeat of your writing, so don't neglect it. Make it work for you.
(3) The grammar subset. If you don't learn basic grammar and you start sending off query letters with big errors in them, then what it says to the person reading the letters is that you're not taking this very seriously. You need to start thinking of yourself as a professional, and part of that is presenting yourself as someone who knows the value of a comma.
(4) This is probably the second most important thing I am going to say. There are other writers who are better than you. For the rest of their goddamn lives they will write rings around you. Perhaps they work REALLY hard at their writing and you have kids and a job and a dog and two cats (not that I'm describing me, you understand) and you cram your writing in when the kids are asleep...okay, this is bullshit. Some people are just better writers. I can think of several people I know personally (coughcough Ann Parker for one coughcough) that make me green with envy. I am no slouch, but you know, they are just better writers. Okay. Deal with it. I can deal with it, and I have an ego the size of Montana. Take pleasure in what *you* write. How you put it together. How you want it say it YOUR way, which is unlike anyone else's way. Do I get pleasure out of reading superior fic? Sure. I also get *tons* of pleasure out of other writers who may not be Nobel Prize in Literature contenders. IT'S STILL GOOD WRITING. It scratches an itch. It might not be the best put together story, but the writer is fresh and is striving to get an idea across and does a damn fine job of it. IT'S GOOD. I LIKE IT. I WANT TO READ IT. ALL OF IT.Does this mean you can be lazy and just slop down what ever comes to mind. NO! I abhor lazy writers. There is no excuse for this. Each project should be a little better. Haven't you picked up a book and thought that the author just phoned it in? They probably just cut and pasted their previous book and changed the names and the verbs. I will NOT read people who are lazy. It shows. You can't hide it. Think about what you're writing.
(5) So you've come to the horrible realization that you're not as good as author (A). And, sob, you'll never be as good as author (A). This is my reality. I don't mean to put up ANY roadblocks because the strides I've made in my writing over the last five years have been phenomenal. Basically from being unable to get a job writing fortune cookies to getting a book published. But still. Like I said, I'm pretty smart, but I can name names who are obviously JUST smarter than I am and are better writers to boot and do we curse them? We do not. WE LEARN FROM THEM. Take an author you admire and PICK APART her/his novel. See how the tension rises and falls, study the voice of the piece, how the characterization is done. A great writer chooses every word with care. EVERY WORD. Nothing is superfluous. IT ALL MATTERS. Whatever is there is there for a reason. Find out what makes this story work. I do this with every piece of fiction and non-fiction I read. Writing fiction has almost destroyed my love of reading because I CANNOT turn off the internal editor. Good writers either (a) just won that mental lottery and can write; (b) work their asses off to craft a story; or (c) both. You can learn from them. They are laying out their craft for you to enjoy and learn. See the bones of the story for what it's worth.
(6) Don't wallow in your mediocrity or flog yourself. I do this all the time, and it is self-destructive with a capital "S." Do not do this. This relates to No. 4 above but takes it one step further. PUSH yourself to be a better writer. Take classes. Buy books. "Bird by Bird" by Anne Lamott is highly recommended. Don't let your talent go to waste. Do you have talent? Yes, you do.
(7) Eliminate the verb "to feel" from your vocabulary. Yes, I do use it, but I shouldn't.
(8) And the most important thing I'll say. You get to say it your way. Relish this. This is what it is all about. You get to have a little contract with your readers that says, "I'm going to entertain you. I am the magician here." You might not have the audience of writer (A), but hey. That's the breaks. I did a signing at a mystery conference, and I got sat next to Mary Higgins Clark. Her line went out the door, and my line was, well, five people and two of them were just gawking at MHC. But my three people were fantastic and really liked my book and were so grateful that I was actually talking to them and was interested in what I had to say about mystery fiction and it was all good. Do I want 200 people at my book signing? Hell yes, but realize that your story is speaking to someone and that someone deserves your attention. They gave you theirs.
(9) Yes, your story is speaking to someone. And sad to say, it won't speak to everyone. There will be people who will not like your book. They just won't. You cannot please everyone. There will be people out there who think you're a mediocre writer, and they might be rude enough to tell you. Or they will trash cooking mystery fiction when you're in the audience (and yes that has happened to me). Of course, thirteen other people said they loved it. Focus on the thirteen that took the time to tell you how much they enjoyed it. You're doing something right.
(10) Listen to criticism. Sifting through feedback and determining what is valid for you and what is not is also an art and takes time to develop that skill. If three people say something isn't working, listen to them. You're not keeping your end of the contract to weave that magic, however, see above. At some point, you will have to make a judgment call. Or sometimes it's just, "I like this and I'm keeping it in," because, after all...
(11) You're writing for you. Write what makes you happy. This should be fun, and if it's not fun, there's something wrong. You should be your most avid fan (and harshest critic). Write what you're passionate about. The passion will come through, believe me, and will hide a lot of faults. If I were given the choice of reading a book by someone whose writing might not be uber polished versus someone who can string a sentence together like whoa but doesn't give a flying fig about what they're writing about, I'll pick-up the passionate newbie every time. The words don't lie. You can't hide. The voodoo is all powerful. So, yeah, write what you love. That love comes through as well as the ennui.