Not sure if it's been mentioned, but I learned a valuable lesson - never clear the cache/data from Google Play Services through the Apps Settings. I did that to clear out a bogus permission that I accidentally installed on my phone when working on an app and it left the phone completely goofed up. Half the notifications stopped working (e.g., I got notified when I had email on two of my four email accounts, but not the other two), some apps would auto update and some wouldn't, all sorts of weirdness. Only way to fix it was a hard reset.