Can i improve my projects structure if so which sources can i use?

I know this is a completly general question, but i'm interested in improving my projects struture, if this is not the right forum i will move to the right one.

Now about what i'm trying to improve, let's suppose i do an MVC or WEB API project in .NET Normally the struture of my project will have the following structure (the DataLayer folder is just a test):

And if i need i use a second project that is a common project, where i have my data layer, using an ORM like entity framework and a lot of functions that i shall use in other projects. The name Controllers is probably not the best because in this case it will be normal classes.

In intend on investing time doing better code, making use of design patterns, shall i use subfolders to organize better my code? If the project is big this turns a bit of a mess. Are there good references out there that point me on a right direction?