Take your photograph in color. Although it seems natural to start a photograph that is destined to look older in black and white, bear in mind that effects such as newsprint and sepia will be easier to create and look richer if you have a broader spectrum of colors from which to choose.
Edit your photograph online. Picnik is a free editor that doesn't require you to register (See References). Upload your photograph and choose "Effects" in the menu bar. You can choose from sepia or black and white and adjust accordingly. You can also edit your photograph in other free programs such as Fotofox, Picassa or with a commercial site's editor, such as with Walgreen's photo-editing software at its website. If you don't know quite how to do any of this online, take your photograph to the shop and ask the photo attendant to show you how to do it in store.
Open your photograph in a photo-editing software package such as Photoshop. In Photoshop, open your photograph, choose "Image," "Adjustments" and then "Desaturate." This makes your photograph black and white. Then select "Image," "Adjustments" and then color balance. Slide the bottom slider to the yellow side to achieve a sepia effect. To further age your photograph, make it a bit grainy by going to "Filter," "Artistic" and "Film Grain." Play with the settings until you achieve a photograph that looks the way you'd like it.