I can only guess based on what they've said about the scores and what I've leanred about scores like this on most sites of this nature but I believe:
The author score is based on an algorithm that includes things like traffic, participation in the site, and a variety of things that don't require you personally to do anything- for example if you start to get a small stream of hits consistently (doesn't have to be a lot just consistent) then it would likely raise your score... They may have something in there that shows module (monetize modules) clicks and since that earns you or the site money and is important I'd think sales would affect score and prove a wizzle is doing well :)
I think traffic is the biggest score pusher upper. I've written articles that had a consistent low score then one day they boost up due to traffic or even likely backlinks being built (by readers) to them... I can't see their algorithm but based on their explanation of how it works these seem to be the hallmarks.
If your author score goes up and you don't know why, check out your individual wizzles/articles see if the scores went up or if more of them have higher scores at the same time (I assume that would factor in too)... stats generally tell you what changed. I think anything that could boost the page/site in any way would affect the score (inbound traffic, inbound/outbound links, sales/module clicks, frequency of articles published, quality (individual article score biorhythm), and so on.
The score is there specifically to help you figure out how to optimize your account/articles it has no bearing on earnings or anything off site (well inbound traffic, clicks, backlinks would) - it's merely a tool to help you see where you (author score) and your wizzles individually (wizzle score/article score) stand. I see it as valuable feedback.
I believe part of it is also publishing (not related to your question here but relevant to the score). I notice when I publish a lot of wizzles pretty consistently (or 1 a day for several days in a row for example) that this affects the author score (because you know they want us to keep publishing and push wizzley into the stratosphere)
(of course if I'm off on anything Chef will correct me *smiles*)...