Recently I have had several friends that have had their twitter, yahoo, or other accounts hacked into and used to send out spam. This can not only be annoying, but could possibly harm your image, or even worse someone could impersonate you and get sensitive medical or financial information about you. So i have recommended to these friends to use a program called Keepass, http://keepass.info/. This program allows you to store all of your passwords, sites, etc in one passworded file. You can store this file on a thumb drive, save it to a online storage or your computer.
Another tip and recommendation I have is to setup a calender event, every month on the same day go through all of your accounts and change the password. With keepass its easy because it can generate a new High Security level password for you to use. This makes it even harder for those trying to gain access to your site to actually succeed in their efforts. Most of these hacks are done by automated bots that use dictionary tools to scan through common words, word alternates, and mixes. This means things are hard for you to keep secure. Long Story short, get keepass, change passwords once a month, never share passwords with anyone.