I follow the notion of spread credit and take blame. For instance I was at work the other day, I work on home entertainment systems, and the guy I was working with turned the volume all the way up on this persons stereo system. When it turned on it was LOUD, way too loud. I figured out what happened and turned it back down and when the homeowner came up I said "Oh sorry I accidentally turned the volume all the way up, sorry about that". My co-worker didn't even know what happened until I explained it later when the client was gone.

I could have been a dick and said "Oh he turned the volume up, sorry about that." But by taking blame it shows professionalism and shows my co-worker that we do things together and work as a team.