Maxims of Quantity:
Make your contribution to the conversation as informative as necessary.
Do not make your contribution to the conversation more informative than necessary.
Maxims of Quality:
Do not say what you believe to be false.
Do not say that for which you lack adequate evidence.
Maxim of Relation:
Be relevant.
Maxims of Manner:
Avoid obscurity of expression.
Avoid ambiguity.
Be brief.
Be orderly.
http://www.lancaster.ac.uk/fass/projects/stylistics/topic12/14cp1.htm