Don't bite the hand that has your paycheck in it.
Don't blame me; nobody asked my opinion.
Don't do today that which can be put off till tomorrow.
Don't force it, get a bigger hammer.
Don't get lost in the shuffle, shuffle along with the lost.
Don't lend people money...it gives them amnesia.
Don't let your mouth write no check that your tail can't cash. - Bo Diddley
Don't look back, something may be gaining on you.
Don't make your doctor your heir.
Don't mess with Mrs. Murphy!
Don't permit yourself to get between a dog and a lamppost.