Keep important papers in a fireproof safe or in a safe deposit box. Here's a link to some information on what you should and shouldn't keep in a safe deposit box (due to its limited accessibility). http://www.bankrate.com/finance/savings/4-bank-safe-deposit-box-questions-1.aspx

 Use a file cabinet or some other type of container to hold your other documents. Office supply stores offer many options, including file carts (which are open on top and typically on wheels), desktop file holders, portable file boxes, crates made specifically for holding files, and even cardboard boxes. Several things to consider when deciding what container to use include: where you will keep it; how easy it is to put papers in it and retrieve papers from it; how secure it will allow your papers to be; and whether or not you're a "visual" person who would prefer a somewhat open container. To simplify the remainder of this discussion, I'll assume you're using a file cabinet. However, my comments are relevant no matter what type of container you use.

 Create broad categories to group your papers. If your categories are too specific, you'll have too many places to search for information. For example, rather than create separate categories for flowers, trees and shrubs, you might want a category called "Gardening." Be sure to name the categories the way you think of them. For example, if you think in terms of "Car", don't file car information under "Auto."

Use hanging file folders to contain each broad category. Place the folders inside the filing container, and put a well-labeled plastic file tab on the front of the each file. Use a bold, black Sharpie to write the labels, or print them with your computer or a label maker - this will make the file name stand out and easy to read.  

Use manila folders inside the hanging folders. If any particular category has a lot of papers in it, manila file folders can help you create sub-categories. For example, for the hanging file folder labeled "Gardening" the manila folders inside could be labeled "Flowers", "Trees", and "Shrubs." The beauty of doing it this way is that all the gardening information is in the same general location so you don't have to hunt through your files for each sub-category.

 Put the most current papers in the front of each folder. This will make the information used most frequently easy to find.

Consider using colored file folders to distinguish various categories. For example, all of the "Financial" files (e.g., Investments, Taxes, Bank Accounts, etc.) can be in green folders; all of the House files (e.g., Mortgage, Maintenance, etc.) can be in blue folders, etc. This will allow you to easily zoom in on the appropriate section of your file cabinet and quickly find the file you want.