How do I buy cryptocurrency using metamask?

Could you elaborate on the steps involved in purchasing cryptocurrency using MetaMask? As a novice investor, I'm particularly interested in understanding the process from start to finish. Firstly, how do I set up a MetaMask wallet? What type of funds or payment methods are typically accepted? Are there any fees or transaction costs involved? Furthermore, how do I select the specific cryptocurrency I want to buy? Are there any security measures I should be aware of while conducting the transaction? Lastly, is there any advice you could offer to ensure a smooth and secure purchase process?