Use open source scripts
Unless you know what you are doing or have a well versed development team in your payroll, it is a great idea to use open source scripts. Open source scripts like WordPress, Drupal, Joomla, Magento etc. are feature rich, powerful and are backed by thousands of coders for update & support
Update constantly
New features or not, upgrade to newer versions of scripts as soon as they are released. Point upgrades mostly fix bugs in the script and are as important as a full version upgrade. If you are not sure whether the new update will break your customization, ask in the support forums and do not wait till you get your customization to be fixed before applying an update.
Use strong passwords
Passwords with your names are longer good enough for hackers.Use a combination of alphabets, numbers and special characters and make sure they are atleast 10 characters long. Apps like Lastpass, KeePass etc. can help you generate strong passwords and to store them as well.
Use Database Table prefix when you go for Word Press
Dont use “admin” username
Use appropriate folder permissions
Restrict Root Access
and for more, go through online articles and tutorials related to website security.