Is your 2014 tax-filing material still in an unsorted stack? Straighten it out now. If the IRS has questions about your return, you'll be glad you put it in an easily accessible order.
Do the same for your 2015 taxes. It will make filing your return next year that much easier.
Your tax organization system doesn't have to be elaborate. An accordion file works wonders for many folks. But if you want a full file cabinet for your tax documents, go for it.
The key is to pick a system in which you can easily file and then find documentation such as business expense receipts, medical bills, charitable deduction substantiation and the like. And once you get it set up, stick with it.