Expounding 1 Timothy 4:12-13 Calvin has much valuable to say about the preaching ministry. Here is just one key quote:

This is the sufficiency, yes, and perfection of the ministers of the word of God, namely, that they be of good understanding in Holy Scripture, and be faithful expounders of it. If they have this, they have everything. But if they wander up and down, now here now there, there is nothing but vanity in them, as we see in those who seek to be esteemed greatly as subtle and fine witted fellows. It is true that they will use much display, and the world will be in a fool’s Paradise with them. But yet there is no encouragement in them, to edify those who hear them. By reading the Scripture, we shall be sufficiently furnished with what we shall want to edify the Church of God with, as is necessary.

Don’t miss that there are two key things here. First, we must be well trained in the Scriptures and stick to what they say. This is Calvin’s main point here. However, at the end (and in what follows in his sermon) he mentions the second point, edification. Our being faithful to “say what the text says” is not an end in itself. It is crucial and honorable. However, the aim is to edify those who hear us. Do not use “I was faithful to the text” as an excuse for failing to engage the people before you in the fullness of life and humanity. To be faithful to the text also requires bringing home the truths contained there in a way the people can grasp, pressing the application so that people tremble before God’s holiness, revile the ugliness of sin, taste the sweetness of forgiveness, and feel the love for God and his people well up within them.

Update:
After posting the above I came across the following in the same sermon:
“a shepherd, if he will do his duty well, and execute his charge faithfully, must not simply propose the doctrine, to say, “This is the meaning,” but must exhort as well. And therefore, there are two things required, namely, that we give good and sound understanding of what is required for the salvation of the faithful, and then that we also add vehemence, to the end that the doctrine may touch their hearts deeply, so that they not only know what is good, but are moved to follow it.”