Eschew obscurantism, redundancy, and prolixity. That is, avoid arcane, esoteric, recondite, or obscure expressions; avoid undue repetition, reiteration, and duplication-reduplication of statements, and, above all, refrain from extreme, inordinate, unbridled, unchecked, and exorbitant wordiness.
YW.
Addendum: dictionaries are your friend. Thesauruses? not so much.