Adults are motivated in ways different from children because adults have a clearer sense of purpose, relevance and goals. May be that's one direction to look other than the dictum: use the language more!

One modern approach has been to use a corpus and find a list of most commonly used words (high-frequency words). From here we can generate a list of the top 3000 words HF words.

The adult student can be informed of this list, and be encouraged to learn the words in that order. After the 3000 is done, do the next set.

I believe this has already been done if you google for English corpora. That way you can simply use that list. I am not sure if a similar project has been done for the HF words used in English in India. I suspect that the Indian-English list will be slightly different since you'd have words like "lakh" etc, not commonly found in other varieties of English.

Best,

Lian-Hee

Thanks a lot for your immediate positive response.I absolutely agree with the solution which you have stated to the problem.

 Dear Christophe Strobbe, Thank you so much for your valid suggestions. In my opinion this works out well to improve vocabulary.

Different strategies can be used for different participants with different needs, ages, settings, motivation and.....I have tried different methods but the best choice was FOnF approach  through textual input enhancement, learning new vocabulary in context through bolding, enlargement or  underling, using different colors or fonts...

Textual input enhancement +written recall is another good way 2 learn vocabulary in context, by asking ur students to write dawn the words that attracts their attention and trying 2 make sentences for them...

Best of Luck