My mom uses a notebook in her purse, I cringe every time she pulls it out. As for security if sites offer Two Factor authentication use it! This is where they send you a text message code, you have an app that generates one time codes or a hardware token. This means that if someone tries to use your password on a 'unknown' device you have to prove who you are with a secondary method in addition to your password. (Chase has this, PayPal ect...) By unknown I mean any device that you have not used to log in yet from, new phone, work computer, new browser, someone else's computer... This is also where "remember this device" comes in, do not use that on anything public or a shared device out side of close family. And last of all, Don't use a Password Notebook that you carry everywhere!