I have moderate success just sharing here on the forums, cause these people already have Tapas accounts usually.In general I post my promotions on any forrum where they just ask for links to your comic, I'll also sometimes post my comic as an example to a topic if I think it might apply As for How I promote heres what my promotions tend to look like:
I start with the title page, then a synopsis of the comic includig rating and genre, then the link like so --->
The comic is about a young girl that gets kicked out of an orphanage for her unpredictable powers and ends up getting taken in by a shapeshifter into a mish-mashed adopted family. she has to learn what it means to be herself, be part of a family, and uncover whatever the family's butler is hiding before its too late!
The comic has got aspects of modern fantasy, mystery, found family, and slice of life (as well as tiny bits of science fiction but thats far from the main focus). I'd probably rate it at PG-13 (specific Pages with PG-13 content are flagged as such in the episode tittles as well)
Heres the link if interested! And if ya like it feel free to ask questions!
Thats just how I do it, I think it works better than just dropping a link cause then the people have some sort of expectation of your art and story when they click!