I am not at 90 yet, but here's what I've tried so far.
1. Write original, quality content that someone will want to read.
2. Make sure to spell check it, grammar check it, and reread it for clarity.
3. Add links to sources on the internet and back to my own hubs.
4. Add an original picture or two.
5. Make sure I add tags and summary.
I am writing many hubs, following those five steps in each one. Over time, the score goes up.
Also do some marketing. Visit other hubs, the answers and forums sections to keep my name out there. Drive traffic to your hubs through your other sites - facebook, twitter, blog, email friends, etc., so you get more views.