2. Too simple
A 12-character password isn't going to do much good if it's something as simple as "123456789012" or "abcdefghijkl". Hackers check for things like that right away.
Even a common phrase like "maytheforcebewithyou" is something hackers look for right off the bat. They have dictionaries with millions of the most common passwords and variations, and they can crack these simple ones in minutes or even seconds using home computers.
A strong password needs to have a mix of upper-case and lower-case characters, along with numbers and symbols. However, you can't just get away with simple substitutions like "Mayth3F0rc3Bw!thU!"
Something like that will slow a hacker down, but modern computers are fast enough to try substitutions like this as well. Your password needs to be virtually random.
Instead of just randomly hitting keyboard keys, however, try another method that makes the password easier to remember. Start by thinking up a random sentence. You can use a catch phrase, quote or even a song lyric like "Tramps like us, baby we were born to run."
Take the first character from each word to get "tlu,bwwbtr". Add some symbols in place of similar letters, so "u" becomes |_|, the "to" from the original lyric becomes 2. Then, capitalize a few of the letters to make a strong password that's easier to remember than a random password: "Tl|_|,BwwB2R".
However, when you have dozens of passwords, remembering them is going to be a problem even with this method. That's why you need to keep in mind the next mistakes.