How to buy NGC coins?

Excuse me, I was wondering if you could explain the process of purchasing NGC coins in a bit more detail. Specifically, I'm curious about what platform or exchange is recommended for making such a purchase, and if there are any specific steps or precautions I should take to ensure a smooth and secure transaction. Additionally, I'd like to know if there are any minimum or maximum purchase requirements that I should be aware of, and if there are any fees associated with the purchase process. Thank you for your help!