Alright, here are some principles i learned in advertising:
1-Understand your audience: Instead of spending resources in all kind of media, is more convenient to focus in the places and sites your potential readership has a higher potential to find you. If you have a general idea of your reader's general interests like action-comedy or goth aesthetic among others ....(What are those interests will depend a lot on your story and style.) you can reach a larger part of the people who would love to read your comic.
2- Ad design: the thing is that more often than not, people judge a book by it's cover.....so design your ads around giving a good and genuine first general impression of what the story is about. Don't sink them in walls of text, more often than not, short and sweet is more than enough to hook them up. Don't lie or people may just hit the "back" button after realizing your comic is not what you promised.
If you make a short video or any other kind of audiovisual media (check your budget first to see what you can afford), the first seconds are key to hook the viewers.....use that time wisely.
3- Stay visible without spamming. This is more easier said than done, but try to find a balanced ammount of ad impressions, teasers and anything that makes you visible. Don't be afraid to be creative. If you have fun and understand your viewership, chances are that you will find them, however, seeing the same thing over and over again can tire them out.....The other extreme of not enough visibility is also bad, because people may not find you.
4- Work on your pitch. This is related to ad design and understanding your audience. The same message can be expressed in many different ways and some of these ways can be more attractive to your audience.
5-Know your product: Maybe you have a comic or a novel to sell, but deep down, you are selling more than that. You are selling an experience. When you understand what kind of experience your story offers, you can express that better and convey it in unique and attractive ways.
6-While this is not directly related to marketing, is an important point to consider: You need to have a product in the first place. If you don't work on your story, all that advertising will be useless if the viewers will only find a page or two. You dont buy the carriage without first buying the horse, so make sure whatever you have is enough to hook them up and to continue working on your story (unless it's already finished)