how do i make file

Incremental compilation is nice, but expressing dependencies between objects, sources and headers is a pain in the ass. gcc -M is utter garbage not unlike GCC itself and generates thirty to fifty useless prerequisites per file in case one of the system headers changes. Gotta make sure, the user might be retarded after all.

How do I write good make files and still have time for actual programming?

Plan 9 C is conventionally written with no include guards, and no recursive inclusion.

If many source files in a project are including the same list of headers, they can be factored out into a single #include "stdinc.h", which doesn't meaningfully violate the convention.

I thought it was horribly barbaric when I was first introduced to it, but now I really appreciate it. On Unix there are always semi-folkloric conventions about the order in which headers should be included, but you'll have a double-inclusion no matter what when one header depends on another.