Hi,

There are numerous books in the marks catering to vocabulary and language building skills. I would suggest you to start with basics in language construction before going onto the complexities. If you are pretty weak in english, then you can buy wren and martin first to understand the ways to construct a sentence. There are easy to read essays in it that will help you further. Gradually proceed onto norman and wilfred funk.

For vocabulary improvement, start reading english newspapers. After that you can read these books.

1. McGraw-Hill Essential ESL Dictionary

2. English Vocabulary in Use Series

3. Oxford Picture Dictionary

4. 504 Absolutely Essential Words

5. NTC Vocabulary Builders

6. Word Power Made Easy