1 Do not store information on your network that doesn't have to be there. There is usually no good reason for companies to store the credit card numbers of customers. Do not store hash from credit card transactions. Access to hash makes it much easier for hackers to get credit card numbers. 2 Don't think that custom software will not be hacked. While it may be true that fewer hackers will challenge the system, it only takes one to beat it. 3 Pay attention to your entire business infrastructureIT and otherwise. Hacking is just one way for outsiders to get inside information. 4 Make someone responsible for installing all security updates. Every company says they do this, but many do not. 5 If you choose to communicate with hackers, do not make promises you can't keep. Serious damage can result.