Update March 2015: I’ve since upgraded this script to be Yosemite-only and have parred it down quite a bit, but built it up just as much. Feel free to leave a comment on the Gist, I’m fairly active there in responding to feedback!
A long while ago I forked a script on Github Gists that did a lot of tweaking to OS X behind the scenes and I used it when I did fresh-installs of OS X. I loved it and it removed a lot of the OS’ annoying “features”. I revised it today on a whim to make it more user friendly. I hope you like it!