My favourite technique isn't to make the sentence itself the password, but the first letter of each word (with some punctuation thrown in for good measure). E.g

My favourite technique isn't to make the sentence itself the password, but the first letter of each word (with some punctuation thrown in for good measure). E.g. pick a line or two from a song, like "All the fear has left me now / I'm not frightened anymore" and that becomes "atfhlmn-infa" (if it's something that insists on digits too then you can easily do a substitution like "atfhlmn-1nfa"). Memorable without being insecure.