I used to shoot almost exclusively in Av mode. Lately I've been trying to shoot predominantly in Manual, mostly so I am forced to think more intentionally about my exposure. I've found this has helped me when I do use the Av or Tv modes, as I do what Scott describes with the exposure compensation adjustment. I think the critical thing is not the mode you are shooting in, but knowing what the camera meter will do (or will try to do) in various situations and compensating (or not) accordingly. Whether you respond to that by staying in one of the auto modes and adjusting the compensation setting or switching to manual comes down to personal preference. For me, working in manual just makes the settings more obvious, as very often I've overlooked the exposure compensation indicator or forgotten I've made an adjustment. There are certain things I like to shoot that pretty much mean shooting in manual 100% of the time. Concert photography is one and the other is when I am working exclusively with on-camera flash as my light source. On my recent vacation, I learned there were times I could have stood to let the camera do a little more of the heavy lifting, rather than me fumbling with the dials in Manual mode. Basically those times when the lighting is not especially complicated and not likely to fool the meter.