My personal recomendations.
1-Make your characters interesting and/or relatable (both are optional, but having at least one is a must if you want people caring about them and by extension, your story.)
how to make them relatable?: give them personality traits and/or conflicts people may relate to.
(A gamer will not be relatable if he doesn`t have common sense, even if they are gamers just like the audience.) Maybe they react in the way the audience would or are exposed in situations we all may have.
Interesting: what is special about them? a gift?. an unusual view of the world?, they are insane? (a nonrelatable character can be interesting too)
How?, give them a personality. No need to know every single detail of their lives, but you must have a clear idea of how would they react in most situations.
Character dynamics: contrasting and complementary characters create an interesting dynamic.
Even characters who are similar in some ways and different in another can be interesting (ex: two stubborn warriors who fight for opposing ideals)
2-Make every update meaningfull. (pacing, pacing, pacing.)
The updates must be relevant and/or entertaining, hopefully both if possible.
Relevant: does it advance the story or the development of the characters in any way?
Entertaining: does it makes people feel something? this can manifest in many forms: a humorous scene, a hearthwarming moment, something awesome and/or satisfying happens, maybe some horror or even a sad scene, but make sure you touch their hearts!
Of course, you can have updates where the purpose is to just build up suspense, make sure the payoff is satisfactory 
Interesting characters and a solid pacing will give people something to talk about. And that is engagement.