From what I gather of the guys and gals who do social media successfully is they have to maintain a constant and active presence on whatever platform it is they choose to use. This does mean focusing on one of them, not all of them, on the unfocused ones you do dumps and link to the place where your main activity is. The other thing it requires is time, the success stories seem to be successful after at least a year of doing it, if not two or more. When choosing a socail media platfomr to focus on I'd suggest the key factors are how much you yourself enjoy it, and the other is if you can use it effectively to gain attention. For instance, if you wanted to grow Youtube you'd make videos with time lapsed work, tutorials helpful hints, maybe telling stories about the place you are mapping, etc. And you'd have to post vids constantly like once a week or more. It's not exactly conducive to map illustration. And what with their insane demonetization schemes it may not be worth it (because making videos takes time and effort). If you were on Facebook, you'd have to gather a bunch of similar themed pages you like and comment and like their stuff as well as keeping your own wall very active with amusing comments and current projects and updates and all that sort of whatnot. I'm not sure Deviant Art is still conducive for this sort of thing, but I'd say if you like Instagrm try and work that system, and try to learn how to work it more effectively as you go along.

Frankly to me Social Media seems more like a PITA than it does anything else, but people obviously do have success with it.