Apple will be releasing Mojave to beta users very soon. If you are or wish to be a Mojave beta user I suggest reading this article on setting up a Mojave beta. They highly recommend keeping all of the systems separate from your current workflow which probably is a good idea. However, I do not do this because I want to see how my stuff is going to be affected by the new OS. My approach is a little dangerous, but it has worked for me so far.