How to buy and sell crypto without a centralized trading platform?

I'm curious about the alternatives for buying and selling cryptocurrencies without relying on centralized trading platforms. Could you elaborate on the methods available? Are there any specific peer-to-peer marketplaces or decentralized exchanges that you recommend? What are the key considerations when choosing such a platform? Additionally, how do these alternatives compare in terms of security, liquidity, and transaction fees? It would be great to get a concise yet comprehensive overview of the options available for crypto trading without a centralized intermediary.