Our general advice is to create new email that you will use only for crypto airdrops. If blockchain project that is doing an airdrop is requiring to register on their site, always use different password. There are some great password manager tools out there. Good practice is to create a new Ethereum address that you will use only for airdrops. You can easily create it on previously mentioned www.myetherwallet.com
The most important rule is to never share your private keys with anyone! The best and most secure way to store crypto tokens and coins are are off-line hardware and cold storage wallets. These devices store your tokens off-line and makes them very safe and hard to hack. Most popular hardware wallets are Ledger Wallet Nano S and Trezor. If you are not able to acquire these devices, it is important to choose wallet where you and only you are in control of the private keys. And to backup your private key on papar and store it on the safe place. Good practice in generally is to neve use same password for different accounts. Do not ever use the same password for airdrops sites and your email.