Learning:
Below are some links to videos. You can watch them to observe how professionals swim and learn techniques from them.
Links:
 How to develop an effective catch in Freestyle: http://www.youtube.com/watch?v=w9FwQA3g_Ak
 Learn Body Dolphin- Body Undulation Drills: http://www.youtube.com/watch?v=txPtnzaAwrY&feature=related
How to swim competitive Butterfly- How to kick in the butterfly stroke : http://www.youtube.com/watch?v=8thnrT3IRFk&feature=related