I'm new to LR4, and I'm trying to understand how I organize my shoots. Should I use one catalog for all my, which each shoot has it's own folder on my hard drive. Or should I start a new catalog for each shoot?
It depends on your style and how much you shoot. If you want images to be easily searchable then creating a catalog for each shoot is NOT the route to go. I'm pushing 20K images (RAW/DNG) on a laptop with 2GB RAM and haven't had any problems. Just be sure to back up often because if LR crashes then it will take the catalog down with it.
I just have lightroom create folders by date and apply keywords on import... very simple to do this way. I also have it backup images to seperate drive also. Creating a different catalog for each shoot seems like it would take forever to find what I'm looking for cause I would have to load each catalog prior to searching.
Google Lightroom workflows and see what will work best for you
I use one catalog per project.
If I was selling images to stock or some other purpose where I needed to do bulk searches, I'm sure I wouldn't do that. But for the project-centric work I do, one-catalog-per is just right.
I catalog per year. Its makes it easy to go back and all 3, 4 or 5 star images from a year. I've been with LR since v1 and my first catalog started to take to long to backup, test integrity and open, etc. But that was after multiple years with everything in it.
I know some people who 1 catalog a month, or 1 per quarter.