(emphasis mine):

Our customers’ privacy and security are of utmost importance to us. After more than 40 hours of investigation, we have discovered that certain celebrity accounts were compromised by a very targeted attack on user names, passwords and security questions, a practice that has become all too common on the Internet. None of the cases we have investigated has resulted from any breach in any of Apple’s systems including iCloud® or Find my iPhone. 

The iCloud accounts that were hacked were likely protected by weak passwords. It’s essential that we all follow these three steps to protect our accounts:

1. Use a strong (i.e. long, with letters lowercase/uppercase, numbers and symbols) random password
2. Enable Two-Step verification
3. Use random answers to security questions (i.e. Where did your parents meet? Don’t say New York City. It’s better to say “feiDTDC_34%^$dhcnBNKK3d(“ ).

You cannot lower the risk of breaches to zero but you should :

For iCloud, you can follow the exact steps on .