Establish a Common Style
Imagine the supervisor sends you a message: “Dear X, Following our discussion yesterday, we will start the new marketing campaign on the September 30th. Please prepare a timeline for the preparatory works as soon as possible,"... and you reply: “Whoopee. Sure mate :)"... It becomes evident that you are at a different level than your supervisor in attitudes and outlook.
Strike a common chord with the supervisor. For instance, if the supervisor uses a formal style, be formal, and if the supervisor is informal, reply similarly without going overboard.
As a rule of thumb, use simple words. Avoid words with two meanings, or the meanings that differ with the culture. For instance, “Moot" in British English means “arguable, doubtful, or open to debate," and the same word in American English means “hypothetical or academic, or of no practical significance." (The Economist Style Guide, Profile Books, 2005).
Understand the supervisor’s tastes and interests, to strike and sustain a casual conversation when the need arises, such as when caught in the same lift, sharing a vehicle, or when at social functions.
Finally, understand the common communication errors when communicating with anyone. Make a conscious effort to identify whether you remain susceptible to such errors, and if so, makes resolutions to move out of such habits.