one mistake I see rookies make is acting like they are in some sexy line of work. Investment banking is a service industry. That means you and your boss work for entrepreneurs who make more money than you and have ideas that actually drive the economy and are original. Communicating with acronyms in most industries makes you look like you are self important or out of touch with the way your clients communicate and what they think about. Either circumstance is not good for a career.
+1, well said