Learn a new word everyday!
Read books... lots of them.... search new words... learn 5 words every week! Easy!
I suggest you use Word Office and right click an adjective and replace it with a synonym they give you. It's a great way to see how you can increase your vocabulary in a story.
Read, then read. Then read, then read some more. Be close to a dictionary for any words that you might not understand. Then read a bit as well.
Try to read books, article or blog. It could help you .
Reading books ,newspapers,articles ,visiting sites and reading new words in a dictionary ..!