how to create a dot file for default mac settings Background

I have a habit of creating new user profiles on my mac that serves different needs (ie recruiting, software development etc). I'm always thinking of ways to make creating a new user less expensive, one is saving all sorts of setting files and saving them in dropbox (ie alfred settings, slate settings, bash_profile, vimrc etc etc).

I also have many settings that I have to issue mac commands for (like this one):

defaults write com.apple.screencapture location ~/Documents/Screenshots   
killall SystemUIServer


How can I save these in a "dot file", and simply have the system read them on load (ie like ~/.bash_profile)?
create a bash script for all the config commands, e.g.

#!/bin/bash

defaults write com.apple.screencapture location ~/Documents/Screenshots   
killall SystemUIServer

store it in /usr/local/bin under whatever name you like
run it once for each new account