But where to go for feedback, and what to do with it? Ideally, you go to other writers whose opinions you trust and respect. Friends and lay people who don't meet this criteria will tend to be vague, too easy or too harsh, and not particularly helpful, because they don't really grasp what you're trying to accomplish and/or how to help you.
If you don't know any professional writers, book editors, literary professionals, you can hire a professional to evaluate your work. If you can’t afford a pro, then find peers—fellow writers or people aspiring to be one—who are at your level and willing to trade serious feedback on your work for the same in return. (Please realize how huge an imposition it can be to ask someone to read your material and give a detailed and honest reaction to it - it takes valuable time, may not be enjoyable to them, and they risk alienating you with what they say about it, or visa versa.)
Writers—especially new writers—need encouragement and people who read their work and offer constructive feedback. Getting demoralized about your work is not helpful, but we do need a reality check and perspective from others—all writers do—and that can be painful. But that's how a writer grows. I recommend encouraging your readers to hold nothing back - and not get defensive or try to convince them they are wrong, which just shuts them down and makes them not want to give more. You should get as much out of them as you can, collect the information, and then determine what to use and what to ignore.
You don’t have to agree with everything they say, or follow their specific guidance. I like to have multiple readers, and I look for what there's a consensus about. On the other hand, being defensive and stubborn may stifle you as a writer, and alienate those giving you feedback. The key is to uncover the real problems and not get distracted by minor/personal whims. For that, you may need back and forth dialog with your beta reader where you ask probing questions to dig down to the heart of the issues.
And then, YOU decide how to fix whatever they have uncovered, through the filter of your sensibility. You want others to help you find the problems, period. Only use their suggested fixes if you really believe in them. If not, find your own. They may be trying to help with suggestions, but it's not their project, it's yours.
Your work has to please you first, but ultimately you want it to please others too. Getting quality feedback is essential to achieving this.