You practice and study, rehearse and get feedback. Drilling is nice but when it comes to developing your speaking skills, is there anything you can do besides landing gigs that will help you get better? Try out your local comedy club. A three-minute set in front of an audience of twelve might seem intimidating but remember that nothing's on the line except your learning. Your goal is direct and clear. You know exactly what the audience wants. Can you make them laugh for three minutes or at least smile? It isn't about taking what you learn and making your talks funnier or seeding jokes through them, it's an exercise in delivery, mannerisms, confidence, and pushing your boundaries. If you can do hard things like being funny in front of strangers, what can stand in your way?