If you've been writing fiction as long as I have, you form a few opinions. Think back to your very first manuscript. Now fast forward to the ideally several manuscripts that you've completed since then. Are you the same writer you were when you reached THE END of number one?
Probably not. If you are, there might be a problem. If you're still working on number one, ask yourself why. And if you're submitting, getting no response or little feedback on your rejection letters, maybe it's time to take a look at that also.
Above all, if you haven't had any luck, can't understand why, and you haven't done so already, you might want to join a critique group.
If you're a new writer, my number one advice is to join one with more experienced writers than you are. While that might sound intimidating, that is the only way (unless you're that rare storytelling natural) that you are going to grow as a writer. You can read every book on the shelf, but until you apply craft and writing technique to your own work, e.g. develop your voice, you won't improve as a writer.
I can't tell you how much I've learned from my first book to my now sixth completed project -- not to mention all the partials stuffed deep in my drawers -- thanks to my critique partners. Comments I received in book number one were -- you've gone into omniscient POV and just blew up your POV character; you have too many POVs; you're in the incorrect POV; you're head-hopping; too many words; weak action verbs; and your research is showing.
And those are just the comments I can remember. If you listen to experienced critique partners, something will happen from one project to the next. Those new writer comments will go away. You're going to find in the next book, they'll move on to more complex writing issues. GMC (goal, motivation and conflict). Why would your hero do that? This action seems out of character? Your protagonist doesn't seem three-dimensional to me; what's his back story? Up your pacing here, this chapter is dragging. Need a transition here....
These comments may seem tough to hear, and often they're downright painful. But they are invaluable to a professional writer. It may feel fantastic to get a critique that says oh, my gosh, I love your writing, I wouldn't change a thing! Nice ego boost, but that comment isn't going to get you published. Some good advice I received--don't fall in love with your words.
Another helpful tip I've learned over the years when you're in a critique group is to listen -- don't argue. It does you no good to try to explain what you meant. Take it all in, sit back and let a partner's words sink in from one meeting to the next. It's your story, and it's up to you whether or not to change it.
Another thing to consider when you're a member of a critique group is: Are they helping? A critique group isn't a marriage. You've joined to help you improve. It's okay to say this isn't working and move on to one that will help you. If a critique group is destructive or seems intensely negative, run do not walk away from this energy. This will only make you doubt yourself further -- and let's face it, there's no one more full of self- doubt than a writer ;)
Not sure how to find a critique group? Join your local writers' organization or ask about them on line. If your organization has Open Critique, go and go often. This may be the best way to establish a new group or to get an objective viewpoint.
These are my opinions regarding critique groups. Like anything in this biz, it's subjective. How about you? What do you value in a critique? What's the best -- or worst -- advice you've ever received? Are you still with your original critique group, or have you moved on? Or have you quit altogether and prefer to write alone?
I'd love to hear your stories and what you've taken away from them. I'm a member of an in-town and an on-line critique group and find their comments invaluable. I feel they make me a better writer.