This is a great thread with a ton of excellent advice. I keep coming back and finding new nuggets of wisdom. Just thought of something I could add that's helped me.
I'll start by saying that building an audience is brutal. I've been at it for years, and I've seen only modest gains. But one thing that has consistently helped me has been the use of color. When I started, my strips were all in black and white. At some point I did something in color and got a great response. So I started using color every week. Since then my numbers have seen a consistent increase, and I get a bigger bump when I post to sites like Reddit. When I post black and white stuff, even now, the numbers drop.
I believe it has to do with post icons. When people scan social media sites, having an icon or image in the sidebar that really pops will naturally grab their interest. For me, adding color achieved this, but it could be making a simple black and white drawing that still catches the eye. The main thing is to stand out among all those other tiny, tiny images.
Anyway, hope this is useful to someone. It sure has helped me a lot.