How do I analyze diction in a poem?Maybe you can help by using Sonnet 73 as an example.

When a reader analyzes diction in a poem they are paying
special attention to the word choices made by the poet.  The reader
should give thoughtful consideration to the denotation (dictionary definition)
and the connotation (thoughts, feelings, associations)
of specific words in the text. The reader is trying to discern why the poet
used the words that he did. Here are examples of diction -- one from each section of the
sonnet.

In Sonnet 73, Shakespeare has a speaker talking
about how he is aging.  Each of the three quatrains use a metaphor of aging to help make
his point.  In the first quatrain, the poet uses the metaphor of life being like a
calendar year -- with old age coming the fall and death coming in winter.  Within this
quatrain, he uses the word "choirs" to describe the now empty branches of a tree without
leaves and without birds.  The word evokes the beauty of a full choir singing and leaves
the reader to imagine how quiet and strange this is
now.

The second quatrain compares life to a single day,
with old age coming in the evening, and death coming at night.  Here he uses the word
"seals."  Seals suggests lots of ideas that relate to death and sleep: the seals are
sealed shut, the coffin is sealed closed, a will can be sealed and made official. 

In the third quatrain he compares life to a fire, with old
age being the last vestiges of the fire as it is being smothered by it own ashes. He
uses the word "consumed" to connotatively suggest that the fire eats the wood/fuel that
gives it life or "nourishes" it as the end of the line says.