We all tend to have at least one New Year's resolution each year–even if we don't call it a resolution. If you have resolved to get more organized or finally do something with that forgotten space in your house, good for you!
The best way to tackle a big job like this is to come up with a plan. Put down on paper exactly what you hope to achieve, listing tasks separately so you can check each one off as it is completed. By breaking down a big job into smaller parts, you will feel a sense of accomplishment as you are able to cross off each task. In the end, you will reclaim some functional living space that you may have lost over time and regain control over a portion of not only your home, but your life.
And if you have more than one big job to tackle, use monthly resolutions. You will keep your sanity by allowing yourself a realistic timeline for each job.