One challenge often faced by organizations is that IT is often reactive rather than guiding the operations. You bring in IT once you face a problem and build an IT solution. Once solution is build, struggle starts to integrate with other parts/ applications. A lot of time is than spent on making different pieces work together, which can be avoided if proper EA practices are in place.
Ideally, IT should look at the system and come up with opportunities of improving existing system like automating ordering system and adding new services like moving to mobile platforms.
IT and Business can than prioritize the solutions/ projects based on value addition. Having a big picture in front, it will be easier to take decisions and less time will be spent in making things communicate and work with each other.
Building a core model is important so that newer services can easily gets integrated. For example if centralized data handling and services to share data securely are already in place, getting a new mobile app to market is much easier than in a scenario where we do not have any such centralized solution in place already.
Creating the core IT model is not easy. You need to take a call what to keep as core and what should be customizable. As a rule of thumb, identify what is fixed and what can be changed/ customized in your business. Based on this information, we need to design which part of design is fixed and which is flexible. For example, in a particular business, product information might be centralized but sales can be customized.
In addition, core model need to take care of that fact which processes can be standardized and what data will be centralized and shared. More- http://kamalmeet.com/architecture/enterprise-architecture-manage-your-data-and-processes/