The best way to create and memorable is to create a string of unrelated words, the string should be large more than 11 characters. Because smaller length of random character can be easily broken than larger length of unrelated words. secure password Ex. is much more stronger than dtvk!pk@279 bottlebaseballsharktrophy because using symbols, numbers and capital letters can make password more secure. but advanced software can search these symbols so what matters more is length of word than randomness of characters. so this strategy of using lengthy unrelated words will give you strong, longer and complex passphrase that is easy to remember.