Before pursuing CSM certification, you should have a fundamental understanding of Scrum principles and concepts. This can be achieved by reading books, articles, or taking online courses related to Scrum. The most common path to becoming a CSM is by attending a two-day Certified ScrumMaster course conducted by a Certified Scrum Trainer (CST).
While not always mandatory, having some practical experience with Scrum as a team member, Scrum team lead, or related role can be beneficial. It helps you relate theory to real-world situations and is often appreciated by potential employers. You'll be expected to participate in discussions, exercises, and simulations to gain practical experience with Scrum.