There really is no one stop shopping for this. There is no one article or book called “How to not write shitty queer characters for dummies”. Authors need to dig in and do A LOT of research.
Tumblr is a great resource. Writing about… lets just pick bisexual trans men? Some of them have tumblrs so follow 20 or 30 or 50 of them. Fill your dash with their voices.
Writing about a particular time period? There are lots of queer history books out there from working class lesbian bars to biographies of famous and powerful people. You will have to hit those books.
Writing about a particular place? Find queer people who live there. Talk to them IRL or online. Ask them what their lives are like.
Make sure you seek out voices of queer people of color. Queer media often excludes their POV so don’t fall into the trap of thinking that queer issues present the same for people of all races.
Read novels and stories written by queer people. Notice how different it seems when we talk about ourselves vs when others talk about us.
Read queer news sites and not just the big ones like The Advocate. You can follow tons of queer sites on facebook and tumblr so they will deliver content right to you. On tumblr I’m a big fan of projectqueer because they post news that is actually for all of us, not just cis white gay and lesbians.
You need to be willing to dig in deep and to do so independently. You should also bring your draft to queer people you know and ask them for honest feedback once your piece is done.
What it all boils down to is that you need to be willing to give this the time and respect we deserve. It’s not easy. If it were, everyone would already be doing it.
speaking as a queer person and as an author who writes outside my own experience, you can also literally just ask
people want representation and want to help people who care about getting it right. if you put out a request, you will find that people come out of the woodwork to volunteer their time and knowledge. so ask!
but remember to be humble and respectful and thankful for their time and effort, to listen to what they have to say, to read carefully any links or resources they give you, to take their critique gracefully, etc.
but seriously. people are sooo helpful if you put yourself out there!