Buy a box or cabinet if your budget can afford it. If your budget can't, find a cardboard box a little wider than a file folder and 10" to 30" long. It shouldn't be higher than the file folder tabs so you can see them. You may wish do dispense with the luxury if you move a lot so you can close the flaps of the box for moving and storage. Next go to a business supply, stationary, or discount store. Buy a good solid hardbound notebook. It must be made to last as long as you expect the file to last, usually many years. Get one about 8 1/2" by 11", so you'll have room to write. It'll be easier if it has a column line down the left side of every page like looseleaf notebook paper does. It should be at least 3/8" thick for a small file to as much as an inch thick if you have a lot to file. Buy as many file folders as you think you'll need.
Sit down with the notebook and a good pen. Skip a couple of pages, then start numbering down the left side of the page 0001 on the first line, 0002 on the second line, 0003 on the third, and so on to the bottom of the page. There are reasons for all those zeros, one is so you can't accidentally put a number on a file that doesn't belong there. The other will be explained in the scenario for computers. Next skip 20 pages if you don't anticipate a large file system, 40 if you bought an inch thick book and anticipate a large one.
In the upper right hand corner of the right hand page you've skipped to print a large 'A'. Count or estimate the number of pages left in the book and divide by 26. whatever the number is that you get, that will be the number of pages you label with an 'A'. Label the same number of pages with a 'B' in the upper outside corners. Experience has shown me that the letters "C, M, S, and T" require a lot of space, while, while "J, K, Q, U, X, Y, and Z" don't require as much room. Unless you anticipate something different in your file, assign a few extra pages to the popular letters, and a few less to the less popular letters. Continue labeling the upper outside corners of the pages to the end of the book. Now you're ready to start filing!
You have this book in your hands right now. You'll notice a "0001" on the cover. You may want to refer to it later, so let's make it the first file folder. Open the book you just numbered to the first page you numbered. At 0001 write "FILING SYSTEM". Now turn to the first "C" page in the book, and on the first line write "0001" in the left margin, then on that line write IRACAF, computer aided file system. Go to the first "I" page and write "0001" and "Ed Sanders" on that line. Go to the first "F" page and write "0001", and "file system" on that line.
Do the same procedure for any other way YOU feel you may think of this file as at a later date. You don't have to label a file folder as I've already done it for you as an example. Put the folder in your file drawer. Now in the future when you want to refer to it, all you have to do is look it up in your index and you'll know where it is instantly. Pick up the first item in your pile to file. Write 0002 on a folder, and at 0002 in the front of the book enter the subject matter. Think of all the ways you may think of it later, and enter them in your alpha index with a 0002 in the left column. It makes no difference that the items you put in your file aren't related to the ones physically located next to them in your file drawer. You'll be able to instantly find them later by looking in the index you're creating. Keep going! It's going to take some time and effort, but it'll sure pay off in the long run!
By the way, I do COLOR CODE one set of files, taxes and things relating to taxes. I just take a red marker and mark across the top of the file folder tab. Because of the nature of the system, the folders on taxes are scattered throughout the file cabinet. That's the one topic you need to pull all the files on once a year, and it's quicker if they're color coded.
Proceed the same as the previous scenario except you don't have a pile to deal with, lucky you!
Proceed the same as with the first scenario except you don't have to buy a cabinet. The first file you label and add to your index will be the first file folder that happens to be in your file cabinet. The first file you label and add to your index will be the first folder that happens to be in your file cabinet. Look at what's in the folder and write the general description of it at "2" in the front of the index book you made. Write "2" on the existing file folder.
(Don't forget "1" is reserved for this book !) Go to the alpha index and write "2" and the description of what's in the folder alphabetically under each letter beginning each word you may think of the subject as later. For instance if the folder contained Life Insurance Benefits you would enter it under the letters "L", "I", and "B". Continue on and index all the rest of the file that already exists in your drawer(s). When you get done with that, start on the pile that is to be added to your file. The first item you pick up out of the pile that doesn't already have an existing file folder to add it to will need a new file folder numbered with the next higher number than the last in your file drawer.
Enter that number at the beginning of your index book with the description of the subject. Enter the subject matter in the alpha index under the various letters where it belongs. Continue working your way through the pile. Remember, it doesn't matter that items are filed next to others unrelated to them. Just take them as the surface from your pile.