How do you get Ethereum on Uniswap?

Could you please explain the process of acquiring Ethereum on Uniswap in a detailed and step-by-step manner? How does one navigate the platform, select the right trading pair, and ensure a secure and efficient transaction? Are there any prerequisites or necessary information that one should be aware of before attempting to acquire Ethereum on Uniswap? Additionally, what are some common pitfalls or challenges that traders may face, and how can they be avoided?