Instead of using ETH you can use wETH. ETH was created before ERC-20 so there are some things that aren’t so smooth when using ETH for all transactions. The wETH token is an ERC20 token. Every transaction on Uniswap wraps your ETH before swapping to the token, so if you are doing multiple txn’s, it’s cheaper to wrap all your ETH first. Otherwise, you’re basically paying double gas! It’s also cheaper to sell into wETH.