I leave this rule for others when I'm dead
Be always sure you're right — THEN GO AHEAD!

As quoted in David Crockett: His Life and Adventures (1874) by John Stevens Cabot Abbott, who indicates that he also often used simply "Go ahead!" as a battle cry, and general assertion of determination. | Unsourced variants: Be always sure you are right — then go ahead. Be sure you are right — then go ahead. Always be sure you are right — then go ahead.

Be sure that you are right, and then go ahead.