English first language

There are many materials available on the Internet for IELTS (academic part), both part 1 (graph/chart description) and part 2 (essay).
For building vocabulary, reading lots of words, highlighting new words and learning phrases (e.g. which words go together, e.g. pay a debt, make friends)

I'm in the same boat. I try to read more to improve my English.

I agree that the easiest way to improve your vocabulary is to read a lot. I try to read newspapers and books every day. Sometimes I hire essay writers. These guys often help me with my letters. They are professionals in proofreading and grammar checking. Useful service for international students.