Keep a record of all new words when you are not sure of their meaning.
Write the words down and keep a list at home. (vocabulary log)
In your log write the words in sentences.(You can check them at Ask a Teacher)
Look up the words in a dictionary and record the part of speech (noun, adjective,etc)
Try to introduce the words into any English conversation you have. Carry with you a list of Words I want to Use so you remember to insert them in your speech.
If you read a lot of texts you might look up the Academic Word List:
Academic Word List