How do I buy DeFi?

Could you please explain the process of purchasing DeFi in simple terms? I'm new to the world of cryptocurrency and finance, and I'm not sure where to start. Are there any specific platforms or exchanges that I should use? What are the risks involved, and how can I protect myself from potential scams? Also, how do I determine the best time to buy DeFi, and how can I store it safely once I've made my purchase? Thank you for your help.