When defining a new website, existing processes and the definition of new processes in the organisation are often forgotten. Only when the website is about to go live, these aspects of implementing a website are tacked. This signifies most of the time adapting the organisation to the system instead of the oposite, inefficient processes causing unforeseen costs etc. New and existing related processes should be mapped on forehand
Sometimes your backoffice systems are used to supply data to the website. When the website uses a database which is fed from different locations, you'will want to be sure the information published on the website is consistent. you may want to adapt your internal processes or even your backoffice system to make sure faulty data will not be published online. When creating interfaces with existing systems, these systems should be checked.
Also , when starting a website, you must be aware of marketing and maintenance aspects of the website, which may signify specific skills that are needed in the organisation.