mysterious_being First thing about writing is - Write because you want to write.
Although there are many genres available here and there are some genres which do better than others, you really need to pick the one which you feel comfortable.
Also if you are purely doing is for Web novel purpose then maybe you need to adhere to the following things-
a) Timeliness of chapter release
b) Regularity - don't miss out on updates
c) Nice long chapters to keep readers happy
d) A nice lucid style of writing
But I would like to stress on Grammar as well because sometimes that becomes a mood killer, even if you have really great stuff. Apart from that just believe in yourself and keep writing. You need to be self-motivated too because it's all about persistence here.