Objects are in C as well, with structures. You can do abstraction like that in different ways in comparison to classes. For example, components are common. Difference being that objects are components, but not all components are objects. Also function objects, aka functors.

I try to organize into specific components and piece them together into a sequential or threaded or both model, depending on what I do. Of course, it is specific to what I do. But there are large C projects that are successful - for example, Linux kernel.