Look up Words You Don’t Know - Many would advise you to read books, magazines and watch shows to learn new words but at the same time it is equally important to look up the academic words you don’t know.
Keep a Notebook for IELTS Writing Vocabulary - It might seem a bit old-fashioned to have a notebook to write down all new academic words and their meanings but it might help you understand those words better.
Practice but Don’t Exaggerate - When you come with a notebook or find an app to learn new words, the only thing left to do is practice the word in real life. In the case of speaking skills, you can take on any topic or question that was recently asked in the exam.
Try Vocabulary Building Apps - Everybody owns smartphones these days and there are tons of apps on play store, app stores that can help us improve our language.
Use YouTube for Understanding - We all use YouTube for entertainment but it should not come to you as a surprise that there are hundreds of channels that provide English skills on the platform.
Understand but Don't Memories all the Time - The best way to understand this is to know about Homonyms which are words with the same spelling, and pronunciation but have different meanings.
Read Newspapers - Reading is the best habit to learn new words and it will also help you to improve your skills for IELTS speaking tests. You can subscribe to a daily or weekly newspaper online or offline and have the habit of reading articles on a daily basis.
Listen to Audios & Watch Videos - The best way of learning the usage of a new word is when you listen to it being used by others. So, you can watch TV programs, news channels, movies, YouTube videos, group discussions, talk shows, etc.
Learn Idioms & Connectives - Use of idiomatic language and sentence connectors, while you speak on a topic, would be effective. But make sure you use them when required and do not unnecessarily try to include them excessively.