Originally Posted by Conker's BFD
Organise by sections in the folders.
I highly recommend doing this. If you're unsure how to organize a folder by file type, open up the folder(s) you want to organize, right mouse click anywhere in the folder, hover the mouse pointer over the Sort by tab and click the Type button.
This is how I keep some of my files organized in my personal folder that's 4.26 gigabytes in size.
Since you have a lot of images, a good recommendation is to do this - create a folder called Images and create three more folders inside of it called 0-9, A-M & N-Z.
Image file names that start with a number from 0 to 9, go into the 0-9 folder, image file names that start with a letter from A to M go to the A-M folder and finally, image file names that start with a letter from N to Z go in the N-Z folder.
Make sure to sort the 0-9, A-M & N-Z folders by file type so that .gif, .jpg, .png etc. image file types are separated into categorizes.