My guidling light has been the (now quite short) list of issues in GitHub. I started by removing all of the stale issues - anything that hadn't been touched for months. If they are real issues, they will come back, no doubt about it.
Then I just plodded through the issues, fixing what I could. There is a few still outstanding, but it's mostly all sorted now.
I've also now got continuous integration using Travis CI which should help with build stability moving forward.