Disclaimer: I'm going to be a hard-ass here, so if you can't take it, don't read this. This is a friendly kick in the ass, tough love, because I want you to think about it. I want you to roll this around in your brain and consider it from all angles.
You're not doing yourself any favors if you can't take criticism. If you're out at the first sign of trouble, don't get into writing. Give it up, if you can't take people not liking your stuff (or if you plan to never let it see the light of day).
If you huff when someone says, "Oh, you write?" with that condescending tone, move past it. If you can't, writing isn't for you.
You're not going to progress if you can't take critiques. You're not going to move forward because you'll be sulking.
I'm not saying listen to all the voices shouting at you to do something different. What I'm saying is that you need to sift through them to find the nuggets that will actually help you. Disregard the rest. Writing is hard, emotional work.
If you're putting yourself out there, expect to be hurt. Develop a thick skin against the trolls, listen to the experts. Take their advice in stride. Research what they tell you to decide if it's good advice and will work for you. Then if it's worth your time, do it.
If someone deigns to read your book, be grateful. That's time they could have spent on something else. Life's too short for crappy books, and I tell people that. If someone takes a chance on your book, or even reads it in the beta testing stage, they've decided that it's worth their time and effort.
Time is precious. You don't want to waste yours. Respect how others choose to use theirs. And if they get through your book, thank them whether or not they liked it.
If someone doesn't like your book, it doesn't help when you argue. In fact, it makes it worse because it strains the free flow of conversation. Both parties need to feel safe enough to continue conversing unhindered by emotions. If you get angry or hurt, they'll be less likely to help you in the future. You've lost a valuable beta reader, and might have damaged a relationship.
Readers aren't there to make you feel good about yourself. They're there to be entertained. If the book isn't entertaining to them, it's not their fault. Like Neil Gaiman said, "When people tell you there's something wrong with a story, they're almost always right."
No one notices the good you do, only the bad. Don't write a book to get accolades or validation from other sources. Chances are, you won't get it. A lot of the time, a story done well is the expectation of a reader, not the exception to the rule. It's not the 'once in a blue moon' experience you want it to be. Sometimes, it's just another book. A story written horribly, however, will definitely surprised them.
That's the kind of attention you don't want.
Don't wear your heart on your sleeve in this process. If you can't separate yourself from your brain baby, you're going to hurt. Not a single book comes out perfect on the first try. Some aren't even good after publication. A personal opinion.
What matters is that you have the guts to try and the intelligence to understand the difference between constructive criticism and someone who's having a bad day.
Remember, this isn't about you. It's about your book. It's about your reader and how they interact with the story.
Don't be selfish, thinking it's personal. Don't be stubborn and unwilling to take a look at potential problem areas. Don't make others feel bad for helping you.
It's not our job to hold you up every step of the way. You'll never learn to stand on your own if you're always leaning on others for support. If you want it, go get it. And do it without expecting praise and gushy compliments.
It's nice to hear genuine praise. It makes us feel good. I get it. Mark Twain said, "I can live for two months on a good compliment."
But don't go around asking for validation and acceptance as a writer. That's a sure sign that you don't accept or validate yourself. You devalue yourself, and you devalue everyone else.
Pick yourself up. Dust yourself off. And get to work because you want to. Because it's what you want to do. Be determined to get better no matter what people say. It's alright to be afraid. It's not OK to let that fear hold you back. Pick up a pen, pop open the laptop, open a new notes document on your phone, whatever your process, get writing, and Don't Fear Criticism.
Criticism is a good thing! It means people are paying attention. It means people have noticed and engaged with your work. And people picking apart your work gives you the best pieces to work with. That might be the difference between the story being mediocre or great!
Welcome criticism! Embrace it! Roll around in it and then put it to work for you!