His style was simple and concise. His sermons discursive and familiar or personal. There was no rigid structure, but a flow, which although not casual was conversational. Calvin excelled in application. It was exhortation, correction, rebuke or comfort and consolation, woven throughout the exposition.
Calvin noted that the preacher needed to speak in a way “that showed he was not pretending.” This gave his preaching a sense of seriousness and sobriety, but not morbidity.
He was not averse to using humor. His humor was often in the form of sarcasm, but sometimes it was everyday funny stuff. “When women who put on make-up come out into the sun and get hot, the make-up comes off and we see the wrinkles. So it is with hypocrisy.”
He believed the Bible was God accommodating Himself to us. So in preaching, the preacher accommodates himself to the people. As a result, he rejected scholastic methods and structures, as well as medieval hermeneutics, and simply explained the text.
His sermons were historical, grammatical and applicatory. He and the congregation would be immersed in an author’s mind for extended periods of time… weaving OT and NT together. His sermons move from “them to us”.
Frequency and length: Calvin preached twice on Sundays, then once M-F every other week. On his “off week” he would lecture M-F in theology.
His sermons usually lasted about an hour (although there are exceptions you can see in the sermons/lectures, 30-40 minutes is also common).
Content: Sundays he preached in the NT; M-F he preached in the OT.
He preached consecutive, expositions, with only his Hebrew OT and Greek NT, without notes, having prepared specifically and generally (e.g., he wrote his commentary on Galatians in 1546 and then preached it in 1557).
Calvin’s delivery has never been speficially described, but his preaching was extemporaneous and probably lively. He himself said that preaching should be lively, “Now this preaching ought not to be lifeless, but lively, to teach, to exhort, to reprove…So indeed, that if an unbeliever enters, he may be so effectually arrested and convinced, as to give glory to God.”
For those interested in seeing samples of his preaching, here are 25 sermons from John Calvin http://www.reformedsermonarchives.com/calvintitle.htm