Before you even pick up a pencil or turn on your calculator, take some time to find and sort out the bits and pieces of tax-related information that I hope you have been collecting all year.
Separate your records into the various categories indicated by the line items on the tax forms. On the income side, for instance, you may have W-2s for wages or salary from your employer; 1099s for interest and dividends; distribution statements (often K-1s) from a limited partnership, small business corporation, estate or trust; and perhaps your own records of tips, consulting fees or income from other sources.
On the other side of the ledger you may have receipts, canceled checks or memos of such things as charitable or political contributions, child-care expenses, energy conservation additions to your home, payments to an IRA or Keogh retirement plan, medical expenses, interest on your home mortgage or other loans, etc.
Some documents may contain more than one item, so examine each piece carefully. For example, a year-end credit union statement may show both interest earned on your share account and interest you paid on a loan. Your annual mortgage statement may show both interest and the property taxes the mortgage holder paid for you from the escrow account. You may want to note any "extra" item on a separate piece of paper to go with other statements in that category, to be sure you don't miss it.
After you have all the pieces of paper sorted out and categorized, take a few minutes to thumb through your checkbook stubs and any budget records you keep for deductions you may have overlooked.
If you have started this project early enough, it might be wise to wait a couple of days before beginning the actual preparation of the return. During that period the sorting process itself may trigger a memory of some major item of perhaps a year ago that you had somehow forgotten.
Only then -- when you're certain that you have all the pertinent items of information available and sorted -- are you ready to pick up your pencil and begin to work.