After last week's Yahoo passwood breach, the tips offered in this USA Today article
are a useful reminder. Two things I found useful in the article include:
1) There's a service to check if your Yahoo email address was part of the leak (link is in the article). According to the article "The breach did not involve Yahoo's core consumer operations." So the vast majority of Yahoo users should be safe.
2) If you're concerned about a hacker taking over your email account, gmail provides extra protection that's similar to protections provided by some banks. Gmail allows users to enable two-step verification.