Fishers of men - Ministers or preachers of the gospel, whose business it shall be to win souls to Christ.

Follow me - Come after me, δευτε οπισω μου. Receive my doctrines, imitate me in my conduct - in every respect be my disciples. We may observe that most of the calls of God to man are expressed in a few solemn words, which alarm, the conscience, and deeply impress the heart.
I will make you fishers of men - Ezekiel 47:8-10, casts much light on this place; and to this prophet our Lord probably alludes. To follow Christ, and be admitted into a partnership of his ministry, is a great honor; but those only who are by himself fitted for it, God calls. Miserable are those who do not wait fur this call - who presume to take the name of fishers of men, and know not how to cast the net of the Divine word, because not brought to an acquaintance with the saving power of the God who bought them. Such persons, having only their secular interest in view, study not to catch men, but to catch money: and though, for charity's sake, it may be said of a pastor of this spirit, he does not enter the sheepfold as a thief, yet he certainly lives as a hireling. See Quesnel.
Some teach to work, but have no hands to row;
Some will be eyes, but have no light to see;
Some will be guides, but have no feet to go;
Some deaf, yet ears, some dumb, yet tongues will be;
Dumb, deaf, lame, blind, and maimed, yet fishers all!
Fit for no use but store an hospital.
Fletcher's Piscatory Eclogues. Ec iv. 5, 18.
Following a person, in the Jewish phrase, signifies being his disciple or scholar. See a similar mode of speech, 2-Kings 6:19.

And he saith unto them, follow me,.... These two brethren had been the disciples of John, as Theophylact thinks, and which seems agreeable to John 1:35 and though through John's pointing out Christ unto them, they had some knowledge of him, and conversation with him, yet they abode with him but for that day, John 1:37 and afterwards returned to their master; and upon his imprisonment, betook themselves to their former employment: from whence Christ now calls them to be his disciples, saying "follow me", or "come after me": that is, be a disciple of mine; see Luke 14:27. And to encourage them to it, makes use of this argument; "and", or "for", I "will make you fishers of men": you shall be fishers still, but in a higher sense; and in a far more noble employment, and to much better purpose. The net they were to spread and cast was the Gospel, see Matthew 13:47 for Christ made them not , "fishers of the law", to use the words of Maimonides (g), but fishers of the Gospel. The sea into which they were to cast the net was first Judea, and then the whole world; the fish they were to catch were the souls of men, both among Jews and Gentiles; of whose conversion and faith they were to be the happy instruments: now none could make them fishers in this sense, or fit them for such service, and succeed them in it, but Christ; and who here promises it unto them.
(g) Hilcot. Talmud. Torah, c. 1. sect. 12. so Dr. Lightfoot cites the phrase, but in Ed. Amsterd. it is , "the judgments of the law".

And he saith unto them, Follow me--rather, as the same expression is rendered in Mark, "Come ye after Me" (Mark 1:17).
and I will make you fishers of men--raising them from a lower to a higher fishing, as David was from a lower to a higher feeding (Psalm 78:70-72).

Follow me. Already disciples, they were now called to preparation for apostleship.