I saw this article today from Inc. it has some great insights on speaking. As someone who does a lot of public speaking, I am always trying to learn and improve my skills. I am always looking for tips and tricks. I think one really important aspect is that the topic you are going to present on or speak about needs to be something you have a lot of knowledge of. You must study, research and understand the content. This will bring you the confidence you need to stand in front of an audience and talk about the subject. This is the foundation. Now this will not necessarily make you a good speaker or presenter but it is where you should start. Once you have the content down then you are ready to start honing you presentation and speaking skills. Below are some good resources to get you started.
Here is the article that inspired this post it is worth checking out. 9 Habits of Highly Effective Speakers | Inc.com.
Below is a good slide presentation from 7 Lessons From the World’s Most Captivating Presenters
Here is another good one from Inc 10 Phrases Great Speakers Never Say
Another way to improve is to watch/listen to others and learn from them. You should troll Youtube and Ted for more inspirational talks. Also here is a good list of The Top 100 Speeches of the 20th Century