All great designers are constantly improving their skills. There has never been a successful designer, or anyone of another profession for that matter, that has stopped at a certain point and said,
Social media image creation sizes.
Free stock photography that doesn't suck. Amen.
HTML cheatsheet. It's like a bible!!! This is totally going to come in handy at work--print please.
42 Web Color Palette Ideas Hex codes | Vale Design (http://www.erinvaledesign.com/leo_on_the_loose/2014/01/42-web-color-palette-ideas-hex-codes.html) more on http://html5themes.org
500 Free Vector Backgrounds #freebie http://designrfix.com/freebies/vector-backgrounds
20 Web Design Trends You Can Expect to See in 2015
15 HD Free Blurred Backgrounds - Perfect for infographics!