CSS is getting variables, nesting, scoping and custom selectors. Preprocessors like Sass and Stylus are dead, long live PostCSS.
Just learned Grunt? Oh you should use Gulp – wait no, Webpack.
Still laying out your sites using floats like a sucker? Flexbox is here!
Just built a project using protocol relative // – that’s an anti-pattern now. Oh and jQuery .hide() is bad for performance, so cut that out.
The tips given at the end of the post are exactly how I (try to) keep up with everything. I would add “Attend a good conference” – such as Fronteers – to that list.