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My advice to a bitcoin holder is that one should have a good idea of his wallet before depositing bitcoins. Having a good idea of which wallets are safe for bitcoin or how you should store your passwords or key phrases and then store your bitcoins.
The advice is very useful but not enough and in my opinion, we need to have complete knowledge before wanting to invest in bitcoin. Not only have knowledge about wallets and how to store passwords, but also basic knowledge about security including how to protect your computer from hacker attacks, viruses, strange links...in general, all related knowledge about bitcoin. We should not ignore anything, knowledge is never redundant or wasted. Always learn and absorb new things, don't be too stubborn and only blame when problems occur.