I'm a designer who writes mostly Sass, Less (CSS pre-processors), HTML, Javascript and usually starts off with static site generators such as Jekyll, Yeoman, etc. While working with developers who code in Python, Ruby, Clojure, I help with the templates. In my free time, I design wordpress themes and write plugins in PHP. I run grunt regularly and bower helps me with components that I need for my designs.
This means my system is littered with Ruby Gems, Python libraries, Node Modules. They are either installed via gem installations, pip, brew or npm. Now you realize that my system is a mess even though it works. I really want to do stuffs in a sane manner, the right way.
So, what are the best practices for installation and management of all the libraries, core tools, etc. for a developer on Mac OS X. Point me to resources that I can read, ponder and practice.
Here is the scenario. You're a seasoned developer and I'm your friend  who just got a new Mac OS X system. I'm a designer who will work with Python (mostly with Django), Ruby (with Rails), Clojure, PHP, Sass, Less, Compass, CoffeeScript, Git, NodeJS, Grunt, Bower, Jekyll, Yeoman and alike. As a friend, you know that I'm not a 'programmer' but a developer-friendly 'designer'. How can you help me setup my Mac? And I don't want to come back again when I get a new Mac in future, I should be able to just transition smoothly from my old setup.
Thanking in anticipation.
If all that  you are worried about is quickly setting up a new machine, use a backup software to setup the new machine.  You can also try to use a custom time machine setup with just the folders that you are interested it.
Best practices for management of a developer system on Mac OS X for non-developers