Best places to promote your fanfictions?

Let's see if I can give the abridged version of this. I've been writing MLP fanfiction since 2011 (mostly adult stuff), but lately I've been wanting to expand into new territory since I'm not as into the series as I used to be. I'd like to publish some stories for Zootopia, Undertale and Gravity Falls, possibly more depending on what I get into. So far I've got accounts for AO3, FF.net, Tumblr (which I've had for years), and Furaffinity. Are there any other places that you use to publish/promote your stories which I haven't listed? Also, is it frowned upon to self-promote with links to your own stories on reddit? Kind of feels like I'm leaving a cave and finding my feet again, now that I'm not writing for one exclusive series anymore.