Learn English idioms and phrasal verbs
There are a number of aspects of the English language that you’re not always going to find in an academic course book. Things like idioms and phrasal verbs are extremely common in everyday English conversations.
If you manage to learn these then you’ll find it much easier to talk and understand conversations with native speakers. Although this is not the kind of language you’re likely to use in an academic essay, it’s arguably just as important to you.