在使用多个.h文件时，在哪里进行类型定义?

I was wondering where I would need to do a typedef when using multiple .h files in c language. I have a project to do and have decided to divide the functions in to two separate .c and .h files to make it easier to locate a certain function. But the problem I an having is I need to define two type using typedef, and the both the header files need to know what this type is otherwise I get errors saying type unknown or something similar. I have tried putting the typedef in a separate .h file.I was wondering where I would need to do a type