Reading - Reading books is the ultimate word frequency list. Reading is great because it allows you to learn and reinforce vocabulary.
Lookup for new words - You should look for new words daily and try to grasp them.
Make a journal - Whatever new words you learned today try to jot them down. You keep revising them so that you don’t forget.
Speak up - Use good vocabulary in your conversation. This will help you to look different from the mass.
Get a good bilingual dictionary - It’s a great idea to look up obscure words you don’t quite grasp that come to you on the fly as you go about your day.
Play games - It’s not necessary to learn with books only. You can also learn while playing games like scramble, and solving different kinds of puzzles.
Reading Idioms and Phrases - Idioms are particularly important since they allow you to express yourself in unique and unique ways.
Learn synonyms as well as antonyms - Synonyms and antonyms might help you expand your vocabulary.
Read from different sources - Reading Norman Lewis's word power makes your vocab quite strong. You can get access to CATKing dashboards where you get videos of vocabulary. As you see a new word jot it down in your diary.