Bitcoin technology is quite secure, taken on its own. The danger lies in the infrastructure that you use for storing it or operating with it. Channels of communications may also be vulnerable to hackers. In the end, there is a human factor - people often do not pay heed to even elementary precaution when it comes to protecting their personal data.

How to keep your cryptomoneysafe? Well, for one make sure you don't use software with flimsy security. It is often the case that people use their cyrptowallet software in the same environemnt that they use for accessing Internet. This doubles the risk of contracting malware.

There is also a trade-off between convenience and security. Hardware tokens are quite secure. Yet they are not always convenient.

You can check out the announcement of the product I am working on, if you are interested: https://bitcointalk.org/index.php?topic=2471742.0

Basically, what I am trying to do is create a hardware wallet that is very secure, yet has convenient interface and can be connected with other devices