This is a great question that we get all the time! This link is for an article written by Shopify (who we recommend using to set up and manage your Online Store) - https://www.shopify.com/blog/16889288-8-steps-to-prepare-your-online-business-for-tax-time
In this article they walk you through everything you need to do to get your eCommerce business ready for taxes and how to file them.
We also have a great article on our blog written by a CPA who also happens to be a student of Drop Ship Lifestyle. You can check it out here:
This should get you started on the right path but please note it’s always best to speak to an accountant about your personal situation.