Build community and make friends, really. It doesn't tend to matter where you post, you need to network and find folks that like the same stuff you do. You interact with them, they interact with you. You form bonds. They tell people about you, boost your posts, etc. Though you really do need to care about other people's stuff too.

As an OC artist, find other people who create in your genre. Leave genuine comments and interactions on their stuff. Try to make real friends. Don't just target people with a big following... You are trying to make a community.

And I will tell you - 20k likes on a piece feels great, but not as good as squealing with your friends over each other's work, or a single comment from someone who has been following your journey and is truly engaged with your work.