What would be great is if Tapas could code something where it automatically makes suggested series based on a reader's preferences. Say for example you like robot based series. If you have 4 or 5 robot series in your library, Tapas then suggests robot series that you haven't read. A push could go out once a week similar to a Daily Snack but instead it lists the last five updates for series based on your preferences that you haven't yet read.
Bloop-bleep-bloop! Hey reader, here are five robot series that updated this week that we know you would just LOVE to read. -Staff
The nice thing about this is because its completely automated staff doesn't have to put in any resources into it other than the initial coding. It also helps solve the situation of discover ability because now readers who will naturally enjoy your series will eventually find it because of their preferences.
Another way to do preferences, rather than library based, is to have some some sort of section where readers can go in and click boxes for what they prefer. I like this this this and this. Then Tapas automatically starts making recommendations based on those preferences. Once a reader reads that series, it won't be recommended again for a while, that way even small series at the "bottom of the pile" will eventually rise to the top because everyone else in front of them has been recommended.