http://www.linuxfromscratch.org/hints/downloads/files/packag...
which explains reasoning for the package manager and how to implement it yourself (in a much less copy-compile-execute manner than LFS itself).
Implementation is a great way to learn but generally people will survey the literature first to understand why things are implemented the way that they are. Understanding what all package managers have in common will allow you to distill it down to the simplest factor and implement that.
A lot of the core utilities and why they are expected should be covered in the standard (POSIX in this case).
I guess what I am trying to say is that implementation is a useful way to learn but it requires you to know the details whereas understanding the literature first will give you a better idea of what to implement.
Good luck with your project.