Righteous speech is characterised by knowing what is 'acceptable' — what is fitting, appropriate, and pleasing. This is wisdom's discernment applied to communication.
Memory phrase: Know what is right to say — and say it.
Talk about it: How can you know if what you are about to say is acceptable and good? What tests can you use before you speak?
Prayer: God, give my lips the wisdom to know what is acceptable and good to say — and the courage to say it.