You should create folders and subfolders to hold and organize your data. If you keep a lot of documents, consider folders for the subject of those documents. Perhaps Taxes, Receipts, Hobbies, House Plans, or similar folders will do.
If you have a digital camera and take a lot of pictures, create folders with subfolders that are named after the type of pictures you've taken: Weddings, Vacations, Wild Parties, Building Our Home, and folders for each of your children and each of your pets.
If you are a freelance artist or run a graphics company, create folders that contain artwork for specific companies or clients. You might also have folders for artwork in progress, finished artwork you can archive, and artwork ideas.
If you have a scanner and are the family genealogist, create a folder named Scans and create subfolders for each branch of the family tree.
If you create music projects for fun or profit, organize your tunes by date created, by name, by client, or by song.
If you have a DV camera and take a lot of video, create subfolders inside of the Movies folder that are named after the type of movies you've created.
The idea is to take a good, hard look at what you use your Mac for and create folders that represent who you are and what you do.
Note: You can also personalize the desktop with folders, and use labels as a colorful way to highlight a folder's name for easy recognition. This will make finding your files faster and easier. You can also compress and archive data you rarely access.