8- KYC issue: I prefer not to do KYC for airdrops or bounties. If their database gets hacked, your passport can end up in Dark web. For exchanges, I always try to use my Driving License instead of my passport for KYC (some of them only accepts passport :/ )
Even in centralized exchanges or gambling sites that involve KYC, there's still a lot of chance your personal information will be leaked.
Another issue to avoid is not using exchanges that ask for KYC, try to find another alternative like using decentralized exchanges.
1- Never ever use an exchange without 2FA: Even the hardest passwords can get hacked easily. If you don't use 2FA you can get hacked... Yep I got hacked - my Bibox account, took hours to block the account, half of my earnings were lost. (it wasn't more than 50$, thank god...)
With or without 2FA, if the platform itself is vulnerable, you can get hacked.