Ive only seen one person do underwater pics, so thats not needed.
I started getting better pics out of my point and shoot when I started using a stand, or tripod and also put the shutter on a timer so you can push the button and get away from the camera before it takes the pic. Your pics will come out more in focus when you do this, because theres no way you can hold the camera that steady.
Playin with the white balance helps too, but not too much or people can tell your messin with the lighting.
Cannon SD 790 IS 10MP, but I still take about 10 pics for every good one.