Usually it comes down to having even lighting on the green screen, which is a lot harder than it sounds - and making sure there's enough space between you and the screen. In a typical home office, it can be hard to find enough space to set everything up the way it needs to be.
My own tip is a bit contrarian: don't use green screen. It's a fun gimmick, but do you really have to look like you're someplace that you're not in your course? I've personally moved to just using nice backdrops used for portrait photography behind me instead. I can still overlay text and images on top of it while editing if I need to.