Getting noticed with a novel is hard. The biggest novels also have accompanying webcomics. I think to get noticed and more subs for a novel, you really have to become Premium or get featured the in the Staff Picks section.
Two of my series have gotten featured in "Noteworthy Novels" (aka Staff Picks) and as a result have gotten a huge boost.
I don't know if you have noticed, but all of the novels that are trending are either Premium, have a comic adaptation, or are featured in the Noteworthy Novels section. So I guess that is the only way.
OR. Win a Writers' Camp and go Premium.
My July Writers' Camp entry link below: