I have read little bit about architecture and also patterns in order to follow the best practices. So this is the architecture we have and I wanted to know what you think of it and any proposed changes or improvements to it -

• Presentation Layer - Contains all the views,controllers and any helper classes that the view requires also it containes the reference to Model Layer and Business Layer.
• Business Project - Contains all the business logic and validation and security helper classes that are being used by it. It contains a reference to DataAccess Layer and Model Layer.
• Data Access Layer - Contains the actual queries being made on the entity classes(CRUD) operations on the entity classes. It contains reference to Model Layer.
• Model Layer - Contains the entity framework model,DTOs,Enums.Does not really have a reference to any of the above layers.

What are your thoughts on the above architecture ? The problem is that I am getting confused by reading about like say the repository pattern, domain driven design and other design patterns. The architecture we have although not that strict still is relatively alright I think and does not really muddle things but I maybe wrong. I would appreciate any help or suggestions here. Thanks !