Someone gave this to me years ago, I don’t recall where I saw it first.  I’ve never seen the book to which it is attributed, so I hope it is cited accurately.  In any event, it is worthwhile, and if it is representative of the book, it might be a good investment.

The Ten Laws of Excellent Speech

From The Teenage Years of Jesus Christ
Jerry Ross

1. Speak Sparingly

He that hath knowledge spareth his words: [and] a man of understanding is of an excellent spirit. (Proverbs 17:27)

In the multitude of words there wanteth not sin: but he that refraineth his lips [is] wise. (Proverbs 10:19)

2. Speak Only After Thinking

Seest thou a man [that is] hasty in his words? [there is] more hope of a fool than of him. (Proverbs 29:20)

Wherefore, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath: (James 1:19)

3.Speak Honestly

Wherefore putting away lying, speak every man truth with his neighbour: for we are members one of another. (Ephesians 4:25)

[He that] speaketh truth sheweth forth righteousness: but a false witness deceit. (Proverbs 12:17)

4.Speak With Grace

Let your speech [be] alway with grace, seasoned with salt, that ye may know how ye ought to answer every man. (Colossians 4:6)

5.Speak Only Acceptable Words

Let the words of my mouth, and the meditation of my heart, be acceptable in thy sight, O LORD, my strength, and my redeemer. (Psalms 19:14)

6.Speak Appropriately

A word fitly spoken [is like] apples of gold in pictures of silver. (Proverbs 25:11)

7.Speak Respectfully

Rebuke not an elder, but intreat [him] as a father; [and] the younger men as brethren; The elder women as mothers; the younger as sisters, with all purity. (1 Timothy 5:1-2)

8.Never Speak Evil of Another

Speak not evil one of another, brethren. He that speaketh evil of [his] brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge. (James 4:11)

To speak evil of no man, to be no brawlers, [but] gentle, shewing all meekness unto all men. (Titus 3:2)

9.Never Praise Yourself

Let another man praise thee, and not thine own mouth; a stranger, and not thine own lips. (Proverbs 27:2)

10.Speak the Gospel Boldly

For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. (Romans 1:16)