Charles Reid, in his book Pulling Your Paintings Together, writes "...you must draw as if you've never seen or experienced anything before the moment you first see your subject. You should literally be seeing for the first time." This reminds me of the passage in the Letter of James, "A man who listens to God's word but does not put it into practice is like a man who looks into a mirror at the face he was born with; he looks at himself, then goes off and promptly forgets what he looked like." Being forgetful and not forgetful at the same time is the challenge.
Elsewhere Reid writes, "...a drawing is like a poem. It suggests and implies, but it never tells a literal story." I like to remember those words.