Two, storing any important information on your phone is a risk. Sure, it is terribly convenient to have credit card, bank, other info on there. But your phone is your device that is most likely to get hacked, most likely to get stolen/misplaced. It is the worst place to keep important/sensitive information.
Three, never lend your phone to an un-trusted person. Never let your phone out of your sight in someone else's possession while unlocked. It takes just a few seconds to install malware on any device. That stranger with the broken-down car that just needs to call a friend? Make the call for him/her. The finance guy that just needs to see xyz? Show it to him/her while you hold the phone.