Another great thread post @vincentprendick!
19.Don't forget to Self-Promote
Self-Promotion is key to growing your fan base. How can it grow if people don't know it exists? It's up to you, the artist, to promote your series in the proper manner; social media profiles, interest groups, comic conventions, get your friends and family in on helping you spread the word, practice advertising using free ads on Project Wonderful, leave freebies/flyers at community centers (library/church) or at comic book stores, and research new methods constantly and stick with ones that work. Construct a compelling elevator pitch (a brief line or two answering the question What makes your comic special and Why should I read it?), memorize it and recite it whenever you're asked to describe your series. Find your target audience and promote in places where they hang out. (ex. Fantasy comic- try joining online fantasy communities)
20.Give Readers a Reason to Stay
To make sure all this hard work of self-promoting pays off and your have readers that'll stick with you, give them a reason to stay. Hold fun contests/raffles with nice prizes (comic cameos, sketches, prints), try Livestreaming so fans can hang out with you as you work, Q & A comics, post WIP/extra content, time lapse videos, Art Requests, fun collab projects with other artists. Later on you may choose to only offer a few of these to supporters, however, first starting out you may want to consider trying these as a way to engage and make lasting fans. And Thank them constantly for their love and support that keeps you going.