The more you do the more you learn from your mistakes. Trying to keep those little cameras steady is the hard bit, one of the best bits of kit I use is the gopro jaws http://shop.gopro.com/APAC/mounts/ja...ACMPM-001.html
. This will grab onto almost anything meaning you can grab lots of different angles.
If hand or pole holding try to get 4-5 seconds of as steady footage as you can, this may take much longer to get but when you think you have that then move to a different angle. If you look at almost any tv show or add and start counting how long each clip is before the angle is changed you will note that 4 secs is often the max.
If you have dolphins etc riding the waves let them play around the boat at a reasonable speed, have the camera ready to plunge in when you drop the speed down. The dolphins will stay close for a short time before you need to get them interested again (more speed).
I personally think by changing angles and keeping the video short it makes them more interesting than just watching a constant run of footage.
I only use the basic imovie on a mac to edit, similar editing software is normally free on most pc's. imovie has several short trailers you can drop a few seconds of video into such as the one Ive already posted.
Maybe we should start a thread on filming tips and ideas