One way I advertise and probably won't be listed, because it's old school. I have business cards for my comic series which I give out at comic conventions, festivals, expos and just randomly. It has all of my links and it honestly works. One thing I've noticed is that a digital advertisement might pass under the radar if you're like me and you're also under the radar in popularity.
Everything is RIGHT NOW and people zombie scroll through everything. But, a physical business card is in your hands, you feel lt. It's like the rock in your shoe, it's harder to ignore.
I made mine into a mini-card, double sided and clearly states my comic series.
I've gotten more response with the face to face, than the digital advertisement.