Personally what I do is have it set to all of the focus points selected that way if I forget about focusing it will do it automatically. Usually I will pick the closest focus point to what I want in focus and use that. Depending on what I am shooting I will probably have to change it often, but it's not that big of a deal because I have my camera setup to do it quick. If you have auto focus and metering both associated with the half click of the shutter focusing and then moving the frame might throw off your exposure. I have metering only assigned to my half press shutter button, and another button assigned to start the auto focus. That's my opinion on the matter.