c#

it is more powerful to design your work with the help of tools. Inside Visual Studio, the tool is the Class Diagram Designer. 

this post does not contains any specific guidelien on how to design interfaces/classes in general, it may only contains the necessary links/resource and etc. on how you can get help from using the class diagram to design classes and etc...

the resource that I wantted to share is here: "Designing Classes (How Do I in C#)"

c# - class designer: facilitate your design work