You may not agree with this, but preaching is “an art” or someone might call it “a craft.” Proper effort must be given to honing the “skill” of preaching and then to each individual “sermon.” So, if preaching is “an art” which requires proper effort on the preacher’s part, then would listening to a sermon also be considered “an art” 
(or “a craft”) that requires proper effort on the listener’s part? (You know…the preaching of God’s Word is one of the avenues of worship for all Christians/worshipers, not just for the preacher.) So, how should someone listen to a sermon?
God honored the Bereans in Acts 17 as a noble (fair-minded) people and then explained why He considered them as such. As Paul was preaching the gospel, (1) they were eager (“with all readiness”); (2) they were welcoming (“received the word”); (3) they were diligent (“searched the Scriptures”); (4) they were discriminating (“to find out whether these things were so”).
During a sermon, are you eager, welcoming, diligent and discriminating? That’s how God tells us to listen to a sermon!