What mistakes did you make, and what advice do you have for others to be careful?
What are the best and worst ways of storing a seed in your opinion?
I ran into such a situation once and I wrote down the seed phase of my trust wallet in a diary. But when I set off on a long journey with that diary, I fell into the hands of robbers. A group of robbers stole my diary along with my luggage, mobile phone and wallet. Despite my best efforts, I could not keep the diary safe from the bandits. So that was the first experience in my life and I have never forgotten that experience till now.
Based on the many experiences of people saving seed keys, perhaps what you have mentioned above might be a bit too dangerous to keep secret keys in your wallet or write them in a diary, yes, humans can't escape the name of forgetting.
From my experience, I created 2 new emails that were not confirmed from various other activities, just created them and I also maintained their security with 2-step verification by connecting my personal telephone number and Authenticator App. And before connecting the Authenticator Application, I also saved the barcode or code from the Authenticator so that at any time if my cellphone is damaged I can open it again.