A good friend has cowritten an ebook – 10 Clever Chinese Idioms which you can get free here. The idioms are written in both simplified and traditional Chinese and they’re explained in detail so you can be sure what and when you can use them for. Allan also created and runs Money in Mandarin, which aims to promote the learning of Mandarin especially by showing how speaking Mandarin and being bilingual can help with your career and life. There’s a number of interesting real-life stories of people who’ve used Mandarin in their work.