Skills that I've learned in my day job have enabled working on the latest version of this site much more simple and pleasurable than previously. I use Gulp, Bower and Continuous deployment to streamline everything.
Gulp
I've been using Gulp for about 6 months (and Grunt for a similar time before that) and it is incredible in that I can automate most of the small tasks that make a site faster to develop and to load. For example, I've started to use uncss which removes extraneous CSS after comparing the html on a specified set of pages with the CSS file and removing any CSS that is not required. Awesome! I use autoprefixer to add in or remove vendor prefixes (depending on the latest specs). At the moment I can specify which browsers I want to support and I chose to have 'the latest 2 versions'. I use gulp-sass which combines and minifies the CSS from the .scss files. It is super-shit-hot fast compared to Grunt. Good use of livereload to monitor my code and refresh the browser when I've done something. No more cmd-r for me! I also remove console.log() and alert() from the JS, lint my WordPress php, and create SVG spritesheets.
Bower
One simple line of code fetches jquery and adds it to your project
bower install jquery
. Before you had to go to the jquery site, manually download, then create a new file in your project and save the new file. Such effort is now reduced to a single line of command line.
Continuous Deployment
I used to use Capistrano and that was incredible but required you to manually type a deployment instruction when you were ready to deploy, and a lot of setting up too. DeployHQ reduces all of that and it monitors Github (where I keep my code) for a signal to deploy the code. So if I push code to a specific branch it goes live straight away. Incredible!