Just sat through a great session at our younger ministers conference with David Cook on preaching in Acts. Audio and video up soon, but for now, here are David's conclusions on Peter's three sermons (Acts 2, Acts 3, Acts 4):

• 'cut me and I bleed the Bible' – Peter's sermons are infused with the Bible throughout. This is our task, to proclaim Christ from the Scriptures. 
• engagement – we respect both the Bible and the people we are preaching to. Answer the questions that the text encourages us to ask.
• courage – too much preaching today uses phrases like 'perhaps' or 'maybe' or 'may I suggest' – these are never present in Peter's preaching
• gospel – Peter never loses sight of the gospel in his preaching
• Peter doesn't rush to imperatives. E.g. first command in Romans is Rom 6.11. Go to indicatives first. Who is God and what has he done? Imperatives derive from the indicatives.