The one thing I have discovered in my internet experiences is to seriously consider my passwords and never use the same username/password for everything!
Many years ago when I was very, very new to the world wide web I used one word as a password for everything. Very easy to remember. I mean, why use loads of different words and then have the problem of forgetting them all the time? All was fine for several years, until key loggers hacked into my ebay account. Of course, the result was that they also accessed my e.mail account and my paypal account. They diverted all my e.mails somewhere else. Their intention was to list unsavoury items and e.bay soon discovered an unusual pattern on my account and froze it. The first I new about it was a telephone call from e.bay that alerted me to the problem. It took ages to sort out, ages to get my e.bay account back and working properly again, and I lost all those e.mails that had been diverted, many of them may have been personal. Luckily I did not lose any money, I was very poor at the time so my paypal account was virtually dormant!
Now, you can use your browser to automatically enter your username and password. I am constantly asked if I want the information to be remembered. This is very useful but I like to have a back up. What would happen if my laptop was stolen? I would need the information to be stored somewhere else so I could still access my various accounts and saved webpages. I have found a useful free software package that I store on a USB stick so I always have all my usernames and passwords available to me. There are many available but you should store them on a separate facility.
In terms of choosing your passwords I sometimes use a password generator as it randomly picks letters, numbers and characters that would be very hard to guess, although that isn’t guaranteed. I recently had an email account hacked that used a generated password. Another way I sometime choose a password is to replace letters with numbers or characters in a memorable word.
Whichever way you choose, always carefully consider your passwords and password storage.
Enjoy the journey.