I made a post on how I permanently got rid of my newton ring issue aka oil slicks. A cheap anti-glare film works perfectly fine. No resistance on the screen and no issue with a water test. No need to spend so much on a Zaggs when a simple $10 or less anti-glare film works great.
My biggest complaint I have with my lifeproof case that I'm not going to bother trying to fix is the damn distortion from the vibration the case makes when the speaker is loud. I love this case but I'm with everyone else that Lifeproof really should have done more research before releasing this.
If you don't plan on using speakerphone or video taping much, you can put a couple of thin strips of scotch tape over the mic on the back. I did that and it solved the buzzing/vibration. I took the tape off so that I could video something (video uses the mic on the back for sound) and I've noticed the buzzing is back.