Have you made something that you think, will not be a problem in the future? here are things that might cause you problem that others ignore
Share private keys with a friend or family - sharing is caring as we all know, but these are the things that we should not share to anyone even close friend and family, since they might turn their back against us, when it comes to money,
Why would anyone share who is not on their death bed or has a gun pointed at them, share their private keys with a family or friend. Trust and sharing have levels and this is the level where one has to draw the line.
Remember password to your browser - This might be look alright since you are using the computer but what if a family use your computer, and browse then suddenly your computer , gets compromise, the data that are stored there might be at risk, specially if there is like keys, or phrase for a wallet.
Honestly, I have most of my password on remember on my computer. I find that it is less stressful when I have to log in. However, I am super cautious about the type of websites where I have it on remember.
Allow others to use your computer as an administrator and not a guest user - Since we are close to someone we allow them to use our computer as a administrator user who can install delete on our computer, this is not safe, they might accidentally delete files or application in your computer, for security, give them a guest user for your safety, this is not a bad things since you don't want anything scary happen when you came back and login, and all your applications and data are gone, because they accidentally delete or remove it.
I have two computers. I use one my most of my crypto and bitcoin related business and other for regular stuff. The one used for crypto related matters is kept in my private and I only have access to it. I don't share it with any other person. It is highly restricted. While the other one could be used by every other person.
Storing sensitive data in your Email account - We have sometimes store data in emails, but what if the account were hack, all the data there will be leak and use, like wallet keys and seed phrase, some store it locally or in an external drive just to be safe , some write it on the peace of paper and keep it in a safe place.
This was one mistake I made in the beginning with Trust Wallet. Since I didn't know what else to do, I saved the seed phrase on email out of connivence or so I thouhgt. I am glad that my mentor cautioned me out it and I found a secure place to save it to. Even though my account has never been compromised, I still feel it is the safest thing to do.
Not using Authenticator or Security Verification for online transactions - although this are now required on exchange or some site, emails , some people forget to enable it on some sites that are not required to do so, like on emails you have a choice to enable it, because some are lazy to do extra step for security that is why sometimes they are the victims.
I do not like authenticators because I am always scared that if I lose my device which has the authentication app, I would have lost all my access to my accounts. And I do not want that to be the case with me. I prefer two-factor authenticator to it.