Best ways to master English vocabulary 
Mike Shelby a former ESL teacher, shares his thoughts on language learning 

Learners can improve their English vocabulary in the following ways 
-- by doing communicative English grammar exercises with daily life content; 
-- by practicing speaking on various topics; 
-- by reading various materials in English on a multitude of topics; and 
-- by listening to audio and video recordings with diverse content. 

It is possible to practice English vocabulary through exercises in listening comprehension, speaking, reading, and writing. 
Do ready-made lexical exercises from textbooks in vocabulary practice. 
Exercises in vocabulary practice can include dialogues, narrations (telling stories), thematic texts, questions and answers in various situations, discussions, talking points, expressing opinions and views on real-life topics and issues, etc. 

Learners can also master new English vocabulary by reading thematic texts on the internet, first of all on everyday topics with important content . 

It is better for easier memorization to write down unknown vocabulary in whole sentences. 
It is very useful for learners to practice telling the content of the texts that they have read. 

Students of English can learn a lot of vocabulary on every topic from thematic English dictionaries. Good thematic English dictionaries provide clear word usage explanations and also a few usage sentences for each word meaning, which is especially important. It is a good practice for students to make up their own sentences with difficult vocabulary for potential use in daily life. Think about real-life situations where and when that vocabulary can be used. 

It is helpful for learners to have lists of difficult word meanings and of phrases (expressions) on every topic with usage sentences. By reading those ready-made vocabulary usage sentences many times if needed learners will gradually master the vocabulary. 
The Longman Language Activator(a unique English idea production dictionary) covers this issue thoroughly. It is useful for learners to make up their own sentences with that vocabulary, taking into consideration real-life situations. 

Thematic general English dictionaries combined with English synonym dictionaries are a valuable tool for mastering English vocabulary logically, comprehensively, and intensively for the real-life needs of learners. Some English synonym dictionaries provide usage explanations and usage examples for words with a similar meaning. 
In summary, thematic English reading materials can be combined with English phrase books, conversation books, thematic English dictionaries, English synonym dictionaries, and vocabulary practice books (with lexical exercises) for comprehensive, logical, and intensive learning of English vocabulary.