if you're going to develop a full website, you're probably going to use every single property described on the already-cited w3schools.
The good thing though, is that you don't really need to memorize the syntax for each property, but just remember that you can achieve a particular result with a CSS property... so that you can look up the reference on w3schools anytime you need to use something you haven't memorized yet.
After doing this job for some time, you'll automatically memorize the properties you use the most.