The biggest mistake I made was helping out management when they were short handed with managers. I took a $10 an hour pay cut in doing so. I got behind in bills. I thought it would help with my resume. But it didn't. Management didn't care and looked for reasons to get rid of me anyway and even made stuff up about why I left. So don't bend over backwards trying to help or think your doing them a favor because they will use and abuse you and throw you out to the dogs and not think twice about it.