Life in poses comes from thought in characters

Post a while back at the artcenter by Mark McDonnell.

story should always be in your head... Imagining what the character is thinking will make your work stand out. There needs to be a thought behind the poses, not just how light falls on form. This is how to get life into your work.
pose should clearly describe who that person is

both a more dramatic or subtle push can be accomplished by focusing on the overall silhouette. This will automatically exaggerate the pose and make it far more dynamic than merely copying what you see in front of you. From here adding the subtleties of what the character or person is thinking will push the drawing into the unique category.

One good rule is to leave the facial features til last, the body language should communicate what the action is in the pose first.