first of all welcome to the forum, and I was in your situation once looking for something to increase my vocabulary and I found it!
I can tell you it is very usefull. I will give you some of the books I found in the library and I think you can find more:
1. The world of words : vocabulary for college students / Margaret Ann Richek.
2. NTC vocabulary builders / Peter Fisher, editor.
3. Vocabulary / Cathrine Hilton, Margaret Hyder.
4. A Way with words : vocabulary development activities for learners of English : book 2 / Stuart Redman and Robert Ellis ; advisory editor, Michael McCarthy.
and you can search for website that can teach you the vocabulary...