Serials have been around a long time, were unpopular in recent decades, and now are becoming popular again. I'm pleased to see that folks have noticed it's a challenging format to write and you want to get several episodes up front. I used to do that with magazine columns, ask for the first four in a batch.
Another vital point? If you're planning to start a series on purpose, pick a complex story, something that will unfold in stages over time or just naturally evolve. Most of my series are things my audience simply asked for more of, so not all of them start out that way, but folks do tend to request more of ideas that have a lot of potential. Sometimes it's a character with an obvious problem to solve, that's just beginning, as in "Shine On." Other times it's someone who's going to keep getting into situations, like Brenda in "An Eyeful of Fire." Then again it can be a group of people whose interactions look interesting, which is what launched Monster House with "Eviction, Noticed" and Hart's Farm with "Welcome to Hart's Farm." There are lots of options, but you seriously have to pay attention to storylines in serials, even if you want to highlight a story of character or milieu. If you don't, you will hang yourself.