I can't offer specific suggestions as your requirements and setup are different from mine, but this is how I organize my images:
- two working HDD's. One contains raws, the other contains processed jpegs. Most of the time only the jpeg HDD is attached to the computer.
- Windows Explorer as my thumbnail program.
- all jpegs are organized into folders according to year, then place/activity, then month. E.G. 2011 > Home > 2011_12.
- all raws are organized according to camera, then year, then month. E.G. Leica > 2011 > 2011_12.
- all jpegs and raws include the camera name in the image name prefix, and I retain the camera's original file number and folder number. So a Ricoh GRD III image would be named 3_100_12345.jpeg
When I find a photo I'd like to edit in my jpeg HDD, I hook up the raw HDD and am easily able to find the image by looking in the appropriate folder. Organizing my raws by year and month makes them easy to find, as I will always know the date a jpeg was taken, and which camera was used.
I used to group my images into 700MB folders as I used to burn them to CD for backup. These days I just hook up extra HDD's and make complete disc copies, so I don't need to observe a folder size limit any more. Depending on how many photos and videos were in any given month, one folder can be several gig in size.
Although I use Lightroom for almost every editing purpose, I do not use it to organize or tag my images at all. One reason is because I move from laptop to desktop a lot, and also because neither computers are particularly powerful. A Lightroom catalogue with hundreds of thousands of images isn't exactly easy to manage. Also, my workflow means that I place all new images into one folder to process, and then move them to the appropriate folder for storage.