You could read magazines online, they would have articles with commonly used language in. If you're interested in fashion there are magazines like Elle, Cosmopolitan, InStyle, Vogue, Nylon. The Guardian is an online newspaper, I don't know if it's available outside of the UK. Young Adult fiction would be good for commonly used words. If you google 'the 100 best young adult fiction books of all time' you will get a good list. I'm sure there are lots of other ways, but I hope these ideas help!