Your home office, whether a desk in your living room or a separate space altogether, should provide some comfort and pizazz while also serving to help organize your work and personal documents.
The first step is to organize, organize, organize. Your desk won't serve you well if you can't find anything without knocking down half of your papers. Purchase shelves or a good filing system from a retailer like the Container Store, Ikea, Staples, or stop by a local discount store. You can find file organizers at 99 cents stores that work as well as pricier versions at major retailers.
Finally you can bring a little of the outdoors in. If you don't have severe allergies, try bringing a plant or flowers to your space. Don't want to swap out new flowers each week? Pick up silk flowers from a local craft store like Michael's. Your desk won't know the difference.