How to manage my header files. [closed]

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I have to say that my package compiles ok. But I've seen people create a different include folder where they place their include file. I find this cleaner and a better practice in general and I want to follow it. The problem is I don't know how to do it without absolute reference. I don't want to use something like that:

#include "../../include/lib/foo.hpp"

my package name lets say it is upm. I want something like

#include "upm/include/lib/foo.hpp"

or without upm even better.

I've tried http://answers.ros.org/question/30425/include-directory-for-other-packages/

but with no success. Any suggestions? And generally how do you treat your header files? What it is considered good practice? Sorry if it's naive and a bit general.