Vincent's NT Word Studies
18. Other (etera). Rather, various, different.Preached (euhggelizeto). Rev., preserves the fuller meaning of the word according to its etymology: preached good tidings. See on Gospel, Superscription of Matthew.
19, 20. Compare Matt. xiv. 3-5; Mark vi. 17-20.
Robertson's NT Word Studies
3:18 {Many other exhortations} (polla men oun kai hetera). Literally, many and different things did John evangelize, euaggelizeto, to the people. Luke has given a bare sample of the wonderful messages of the Baptist. Few as his words preserved are they give a definite and powerful conception of his preaching.