Dear Isra,

I'm going to let others chime in on your question so I will just address the diagrams portion.

As a business systems analyst you are not unlike a builder who has many tools at their disposal with a few caveats:

• The more tools you know how to use the better you will be able to serve your customers, you would be able to provide better quality, and do the job quicker.
• You need to know what each tool is for and when to use it and when it is not appropriate to use.  The more you use a tool the more you'll discover its best uses.  For example: you would not want to use a table saw when all you need is to break a stick in half for your campfire.

As with any other craftsman, you there a two types of tools:

• Tools which you have and know how to use.  If these can do the job use them first.
• Tools which you have but don't have much experience with.  Don't be afraid to use (apply in practice) some of the modeling techniques you learned in the classroom.  The more you use them the better you will get.
• Tools which you don't have.  In the case of the analyst, these are techniques and modeling standards which you have not learned about nor used.

So - make sure you keep adding to your toolbox and get your new tools dirty (used).

On to your specific question...

Stakeholder/Customer Centric diagrams allow you to model the business need, problem domain, and requirements in order to ensure you have a  good understanding of what you are trying to solve.  Note: while these are 'customer' centric, the technical team and developers can learn a lot about the customer's need from these artifacts:

• Business Objective Model which help you identify the key drivers of the project and the key customer objectives.

• Feature Tree & Functional Decomposition allow you to dive into the next level of detail in order to identify the logical groupings of features and functions needed to be addressed by the project.

• Process Flow Diagram allows you to understand the problem domain in the context of the existing business process (AS IS) or the proposed/re-designed business process (TO BE).

• Business Entity Model allows capture and validate the key "things of the business' aka business entities which are involved in the problem domain.  This would generally be a class diagram showing business entities (not system classes). 

• Decision Model allows you to model the business decisions down to the most low level business rules in order to clearly understand how the business decisions are made.

System/Developer Centric Diagram are created once the problem domain is understood at the desired level or breath (scope).  These diagrams help to document system design decisions and solution direction.  Note:, don't discount these diagrams as not being understood by the customer.

• Context Diagram & TAM Block Diagram (aka Ecosystem Map) show the key systems and/or system components participating in the solution.

• Data Flow Diagram (DFD) shows how the information flows among the various systems components giving an understanding of how data is transformed.

• State Transition Diagram can be used when the system and/or system objects have complex states which need to be tracked.

• Sequence Diagram would be used to show sequence of interactions, over time, which will take place in order to accomplish a specific scenario or flow.

These just a few tools which you can use, there are many more.

Happy Learning!

Adrian