I'm new to all this (well, been taking snapshots for several years, new to "thinking" about photography). I've had several ways I've organized my files. I've done it with folders by years and subfolders by months in the past, but then had quite a few photos some months to look through finding something and very few photos in other months.
I think I've finalized my organization now that I've purchased more than a full auto digital camera and I've taken more photos since Christmas than I have between buying my first digicam in 2002 to this past Christmas. I have a separate hard drive in the computer that I put all my photos. On that drive I have a folder for Photography. Within Photography, I have seperate folders for "Documents", which is various literature I'm collecting on the web and such, "New to Sort" which is where I put all my photos straight from the camera to give the initial look through. Then there is "Photos", which obviously are all the photos, and "Videos", which is also obvious and I refuse to explain

.
Ok, first I download my files from the camera to "New to Sort". From there, I either use a thumbnail viewer to quickly look at the photos and rename them according to the subject of the photo (usually an object, structure, name of a person, etc.). Or, if I have many of say my youngest daughter, I move them all over to a subfolder so I can batch rename them later. Using a thumbnail viewer makes quick work of this. After giving them a name, keeping the numbered name that the camera gives them as well, I batch rename them again, but all at once now to add the date at the beginning. My naming format is "YYYY.MM.DD subject DSCFXXXX.jpg"
Ok, so now they are all renamed and they get sorted in the "Photos" folder on the root "Photography". In Photos is various categories as I no longer have year or date folders. This allows me an easier time to look for something rather than just a date. The dates are now already in the file names. It will be easier for me to just list an example of my "Photos" folder structure.
Within the Photos folder
..Animals - which includes birds, fish, anything alive and breathing that isn't human
..Auto - subfolders follow for misc auto shots and individual autos that I own
..Events - within events are folders for each individual events like "year.Christmas", "year.birthday.person", "year.BAMS" (which is specifically the local RC airplane club's show each year) etc.
..Family - this contains the most photos and has year subfolders. All family member's photos are in here, but I think I'd like to do better with this, like maybe sort by person or something.
..Floral - anything that is plantlike. Plants, trees, brush, flowers, etc.
..House - Everything that has to do with the house. Shots of the backyard, the house, remodeling, etc.
..Landscape - I call it landscape, but it is more than just landscape. Objects and structures are here as well, anything that is taken outside that doesn't reside in the other specific folders. Within this folder, the photos are sorted in subfolders such as "Bridges", "Farmscapes", "Structures and buildings, and Industrial", "In the Sky", "Waterscapes", etc.
..Misc - One final categoried folder underneath the Photos folder. This is everything that is just general and doesn't fit with all the rest.
I have an "Edit" folder in every subfolder so that I can save files for print or upload after doing any destructive editiing so the original is saved.
From this all, if I want to backup, I just backup the single folder "Photography" and all of my folders and videos are backed up. Unfortunately, foolishly so far, I have not backed anything up. I think I plan to backup twice to CD/DVD so I can take a copy and keep it at work. The only problem I have found with CD's is, I've had some CDs that are not readable in subsequent new computers because they were burned in very old computers. Perhaps the software that I used I no longer have or something, but I've lost stuff over the years because it was burned onto CD and my current computer can't read it.