<span>If the question is asking an overall approach to the Declaration of Independence, the first step has to be a mindset that asks "What was Jefferson saying." In doing so, the Preamble sets the rationale behind the move to independence and the "injuries and usurpations" the specifics. However, no matter what, an understanding of the historical context is imperative.
However, if the task is asking to break down each sentence in the Declaration and relate it to purpose, that would take a while here.</span>