How to write a story that doesn't suck

Representation

Representation is incredibly important when writing a story. Representation allows different people to see themselves in a character. It's a chance for someone to see someone like them as a hero.

Representation can mean a lot of different things. And you have to ask yourself, what am I trying to include? Is it the LGBT? Racial representation? Religion? Body types? Masculine women? Feminine men? Gender in general? Age? Disabilities?

In order to represent something, you have to know it well. If you want to make a character with autism, but you don't have autism yourself, don't write your story around their autism.  Even if you've researched it well and know a lot about it, you can't truly understand what it would be like to have autism and you may risk including myths into your representation. You can have characters with autism, but if you don't have it yourself, avoid expressing it from their point of view. Don't make it about their autism. Simply make them a character who has autism, and let them be human.
(Also you can just hint at it but not explicitly say it so it feels less about their autism and more like the character is just a character.)

Writing LGBT is the same. Don't write a book about being lesbian if you're not lesbian yourself.  But don't be afraid to have lesbian characters!  Avoid stereotypes, they can be harmful. Here are some ideas of representation the LGBT wants to see, and some things to avoid:

-The "gay best friend" is an ugly trope. It's in just about every 2000s romcom ever and it just feels like they only exist to be a token character. (Aka, not a good thing).

-Have queer characters in healthy, good, long lasting relationships.

-Not all kids of the LGBT have unhealthy relationships with their families. I see a lot of people make their queer characters have homo/transphobic parents and then abuse them with that. It's ok to have characters with bad family dynamics, but remember that's not how it always works out in real life. Coming out to your parents doesn't mean you're now kicked out. That happens a lot less than you think.

-Don't make their angst (if they have angst) revolve around them being LGBT. Unless you know what it's like and you're writing from experience, this is something you should avoid.

-Binders exist.  If you have a trans boy or non binary umbrella character (AFAB), it's good to allow them to get a binder. Making them use bandages or duct tape is cliche, and may give unhealthy ideas to a reader. Now yes, trans people AFAB will use bandages and tape in real life, but.... Don't use it for every character. It's really not healthy.

-Have aromantic and/or asexual characters stay aromantic and/or asexual.  Having them fall in love in the end is almost like your saying aromantic and asexual people don't actually exist.

-Have queer people be treated with respect.

-Don't sexualize your queer characters. In other words, if you're a straight cisgender girl writing about two gay men, don't make it sexual. And certainly don't write about them having sex because it's usually incorrect and makes queer people very uncomfortable.

-Transgender characters don't just magically transition. It takes time. It's a long and expensive process. 
(On this note, I'd like to say that I am in fact a trans man.  It really does hurt to see people make their trans characters just magically transition. I've seen someone have their fifteen year old trans boy character already have top surgery and testosterone and be fully transitioned. That hurt. So you have to be aware that 1. Transitioning is expensive. 2. Children usually can't transition and if they do they HAVE to have parental consent. 3. Kids can't get surgeries until their 18 I believe. 4. Testosterone/estrogen takes time to become affective and it varies from person to person.)