I only shoot RAW. I've read that another approach is to shoot casual pics in jpg and serious pics in RAW--I'm not sure how you know a photo is serious until you see it and discover you LOVE it!!! Occasionally--very occasionally--I will shoot in RAW plus JPG . . .
BTW: Any of my images could be considered serious. Of course, some are more important than others...
I shot in RAW + JPEG before I had enough confidence to shoot RAW alone. As long as I have acces to a RAW conversion/image editing program; I will shoot RAW alone! RAW + JPEG files are a bit large and are IMO not needed...
Here is a neat tutorial on RAW from my favorite photo website: Cambridge in Colour...