I'm starting a new project working with a client who already has a decent website. It will be really important to learn about the users and understand what they want/need that isn't already provided.
I've made personas before and they've always been helpful, but never extraordinarily so. They seem to be a really powerful tool and I want to make them as useful as possible this time -- probably the difference between a helpful redesign and another 'blah' layout. What little detail or trick makes personas especially useful for you?