I've recently just started record keeping for a sole proprietorship small business that is based out of a home with the use of a personal vehicle, I was wondering what all can be deducted on the income taxes to get the most back for the client? Also, I'm aware that self-employment taxes and quarterly taxes are required. How do I go about paying these taxes to avoid any penalties and how is it calculated on how much is owed?

Your help is greatly appreciated.