I had similar problem, I had to leave two jobs due to this problem as i was not able to express my thoughts clearly. One of my friend, who was doing MBA from a well-known University in India, suggested me to write Blog posts. And also suggested to share them in the friend circle. So i did the same. Soon, my friends started to comment on the posts, this helped me to learn about how to convey my thoughts in simpler way to anybody. Also i learnt that, a simple sentence works best rather than complicating it with selecting a range of words to say a simple thing to someone.