Beware of scams.
A legit Airdrop never asks for 'Private Key' or 'Fees' or 'Donations'. If you spot an airdrop asking for any of the things mentioned above, avoid it. There are plenty of good fishes in the sea, focus on catching them.
Security Tips:
1. Do not share private keys with anyone else.
2. Do not save passwords or private keys on an online drive. Not even in the encrypted mode.
3. Keep strong passwords with a combination of at least one UpperCase Alphabet+Lower Case Alphabet+Number+Symbol. Such strong combinations are almost impossible to crack.
4. Do not use common words as passwords.
5. It's better to use at least 15 characters as a password. (I'll go for 20)
6. Never delete an old wallet.