What are the most important steps for enterprise architecture and what are the most common challenges?

1. Simplification
2. Easy ops
3. Cost optimised 

One of the major challenges is the aligning enterprises architecture team with business team on their requirement as per organisations long term strategy, as most of the changes done to meeting short term business goals and have major effect on the enterprise’s architecture.

Enterprise architecture (EA) is a strategic approach to designing, organizing, and managing an organization's information technology infrastructure and business processes to achieve its business goals. It involves defining the structure and operation of the organization and aligning business strategy with IT strategy.

To start, I am not an EA.  But, I expect the EA team to contribute by defining and holding firm to an efficient and cost effective application and technical infrastructure.  They should root out redundancy and recommend new products and services to make our business more efficient while also holding the line on unnecessary costs.