There are 15 LGBTQ+ specific instances on the joinmastodon list. More which aren’t on the list, but any of these are a place to start. joinmastodon.org/servers
6 on calckey’s list calckey.org/join/#lgbtq+. The main devs for Calckey are very LGBTQ+ friendly.
You can browse the local feeds of instances you’re considering to see what others on that instance tend to post. More important IMO is that you find an instance whose moderation policy suits you. But you can always migrate to another server so don’t over think picking one. Sign up, follow lots of hashtags and groups (in the Explore box, type in # or @ followed by various keywords for your interests to get started), follow lots of people.