DON'T allow
the conclusion to become merely a restatement of the thesis
with a couple of linking sentences beforehand.
DON'T view
it as merely an ornamental way to end your paper - its
role should be to justify your paper at the highest level.
DO analyze
how your argument has changed as your paper has progressed.
If you haven't proven anything more than merely what you
mentioned in your introduction, you haven't really said
anything at all. Throughout the course of a good paper
new subtleties of argument ought to have manifested themselves,
and the place to integrate all these subtleties into a
new, more powerful statement of your thesis, is right in
the conclusion.
DON'T begin
your conclusion with the opener "In conclusion...".
That makes your paper awkwardly self-conscious and contrived,
rather than naturally unfolded.
DO attempt
some sort of unified closure, with respect to what you
set up in the introduction. If you used one of the previously
mentioned clever introductions, make reference again to
the quote, questions, or anecdote you incorporated.
DO consider
linking your argument to a more universal idea, analyzing
its relevance with an eye on the new angle your argument
proved.