There are certain do's and don'ts to writing. If you feel as if you aren't doing your best on essays, maybe you're using more of the don'ts. Here's a list to guide you to do the do's. Add what you discover in failing or accomplishing from either your own writing or the work of others. (Don't forget the high scoring essays on AP Central)
In rhetorical analysis, do elaborate on the effect of the strategy.

Do be descriptive in your writing.
e.g. Don't just write, "She causes emotion." but "She utilizes forceful emotional appeal."

Do organize rhetorical analysis essays either by the passage's development of its argument or by specific rhetorical strategy.

Be specific!

When stating your stance, give your reasons for taking this position.

In synthesis essays, make sure that your argument relates to the sources. Don't just come up with an argument that has no relevance to any of the sources.

Do draw the reader in.
Look at this example

Do address the refuations.

Do try and have a "conversation" with the sources in a synthesis essay. What would they say to your stance? Why do you disagree with them?
6 steps towards success

In your arguements, give many examples, but make sure they support your argument and are specific.

Do remember that as long as you support your argument effectively, there is no penalty for taking a position that differs from your reader.

This is taken off of the 2009 argument essay commentary.
"does demonstrate a consistent and sometimes impressive
control of a wide range of the elements of effective writing: the student has a rich vocabulary (“engender,”
“literary construct”); uses metaphor (“rousing talent from slumber”); makes clear and clean transitions (“of
course,” “on the other hand”); understands parallel structure (“stimulate, force, and sharpen,” “It does not
simply request a response—it demands it,” and “are always fed . . . are always happy”); and displays a
facility in using dashes and parenthetical phrases"
Don't quote a whole sentence unless it is cruical to your argument.

In rhetorical analysis, don't just write "diction," be specific as to what the writer says and what effect this has.

Don't write "%," write out "percent."

Don't oversimplify either your own argument or the sources of a synthesis essay.

Don't write any sentence that does not support your argument. No matter how good of a sentence, CROSS IT OUT.

Don't use ambiguous pronouns. Be specific as to who is doing what.

Don't lose track of time. Time is crucial and you need to manage it to have time for a developed conclusion.