as far as im experienced with other platforms. NG is very diverse from artists point of view. its very hard to make a small fanbase thatll follow your stuff. instead, your stuff gets thrown to the frontpage to hundreds of people that have a different taste (or no taste duh.)
very hit or miss situation here. collaborations are definitely the way to keep the audience fairly at the top, even if you post speedcore.
talking bout speedcore. the genres on the other hand are a thing to look at in detail. most popular genres tend to be Video Game tracks or lately Drum and Bass (showing a small renaissance.) so yeah. i guess that can be a small factor that will affect your listener count.
LD-W
I wouldn't be too concerned about track scores, as pieces which get front-paged tend to attract a small number of users with very high voting power who decide to just 0-bomb absolutely everything in sight for seemingly no reason at all. If you're online more often around the time of one of your tracks getting front-paged, keep a note of not only your score/votes ratio, but others on the front-page aswell. What you'll find every single time is that if your own track score goes down massively in one vote, everyone elses is aswell around the same time. It happed the other day when all of our AIM tracks were front-paged, and it ended up with around 15-20 tracks being downvoted all at once. So it seems less likely that someone's doing it for easy-XP, and more the case out of spite.
Main things to do to keep activity/engagement up regardless is to stick close to the audio community, network abit between everyone, and keep on top of entering contests when you're able to!