How do you airdrop tokens without getting flagged as spam?

With so many spam airdrops out there, how do you do it so that your tokens don't get flagged or just ignored? Because I've seen some wallets automatically hide unknown airdrops, and platforms like Etherscan even mark some tokens as spam.

So, what would be a way to distribute tokens more effectively? Does metadata tagging help, or do people still ignore airdrops regardless? Would an opt-in system work better, where users decide to sign up to receive tokens?

Also, I've already used this bulk token sender that's supposed to save on gas taxes and whatnot, but are they better for large distributions? Or do the same risks apply?

If anyone has experience with airdrops that didn't get marked as spam, I want to know what works for you.