Create a dev version of my Magento e-commerce website

I'm the owner of Dagobear, a brand of underwear for men. We sell online through our Magento store. Today, I'm directly working and updating on a production version of the website, which I know is bad. I've got a virtual machine ready, but I need to duplicate the prod. version and place it on my dev virtual machine. I'll give access to database and sftp, I just need you to make sure you're making a clean and working copy of the current website. Second thing : If you have any idea about how to make it easier for me to work on the dev website and apply the update on the prod version, i'd take it too.