Sensitivity readers are good.

Also, try reading work in your genre by people from the community you're interested in representing, if you can find it. It's not always easy.

And remember this.

A straight person can write a very good queer character.

But they cannot authentically tell a queer story.

In other words, don't make your queer character's story about their queerness. If you want to write a queer protagonist, focus on the fact that they are also, say, a noir detective.