Beloved: Beloved, αγαπητε: strong:G27, is in the vocative singular, and therefore refers to Gaius.
follow: Rather, imitate μιμου:. Exodus 23:2; Psalms 37:27; Proverbs 12:11; Isaiah 1:16-17; John 10:27, John 12:26; 1 Corinthians 4:16, 1 Corinthians 11:1; Ephesians 5:1; Philippians 3:17; 1 Thessalonians 1:6, 1 Thessalonians 2:14; 2 Timothy 3:10 *marg. Hebrews 6:12; 1 Peter 3:13
He that doeth good: 1 Peter 3:11; 1 John 2:29, 1 John 3:6-9
he that doeth evil: John 3:20