What's the best way to buy ETH?

Could you kindly elaborate on the most effective approach to acquiring Ethereum, or ETH, for those interested in investing in this cryptocurrency? What factors should one consider when choosing a platform or method for purchasing ETH? Are there any specific steps or safety measures one should take to ensure a secure and smooth transaction process? I'm particularly interested in understanding the best practices for buying ETH in terms of cost-efficiency, user-friendliness, and security.