How can you animate a character holding something? Picking up a cup? Pointing a gun? Drawing with a pencil?
Good question. Here are some videos that explains proper constraining in Maya. I am actually surprised this is out there for free considering how great these are. This is a much watch.
Constraint Demo 1: The Basics from David Latour on Vimeo.
Constraint Demo 2: Prop to Hand from David Latour on Vimeo.
Constraint Demo 3: Hand to Prop from David Latour on Vimeo.
Constraint Demo 4: Two Hands to Prop from David Latour on Vimeo.
Constraint Demo 5: Two Hand Hybrid from David Latour on Vimeo.
Constraint Demo 6: Tumbles and Swings from David Latour on Vimeo.