What has worked for me:

* Be aware of "signal-to-noise" ratio in your communication. If you want to say something - say it simply (as best you can) and then stop. Don't dilute your point with unnecessary prefacing or qualification like "but that's just my idea... oh I'm not really sure if I expressed it clearly". You will be very tempted to do this, but resist the temptation and let the silence sit a while, give people time to absorb your comment and to respond.

* Have faith in the approach of "practice makes perfect", or if that doesn't work for you - an "iterative approach", whereby each time you try to articulate your thoughts (and probably fail initially - that's OK), the NEXT time you do so, you will be just that little bit better. You don't need to focus so much on making it perfect each time - that just reduces your practice frequency and will feed your anxiety through analysis paralysis.

I feel that I've been good at writing for a long time. But that's only because I'm old and started reading and writing a LONG time ago.

So...

Read, read, read, then read some more. Take notes on what you read. Since you want to work on your thoughts I'd recommend sticking to non-fiction essays and more specifically editorials. These are examples of people putting their thoughts together.

Put down that social media, put down those forums (esp HN), put down reddit and imgur and facebook. Stop watching TV and movies, edutainment and commercials in sheep clothing. They won't help you. I mean, you can't do this 24/7, but if you find yourself with some "free" time and can choose what you want to do, don't just be a couch potato.

Write, write, write, then write some more. Doesn't need to be a lot and all at once. But regular writing, even if it's only 50 words is necessary to get the skills.

If you're not good at it, it's going to be a lot of work. But you're driven so you'll be fine if you put in the time.

One specific thing to level up your expression is to resist using the word "like".

Some people use "like" endlessly and I've found it's a sign that they're afraid nobody understands them, so everything they say is an analogy or metaphor to try to relate to the other person.

It could also be because the person is not taking any time to formulate what they want to say. Which leads to a ridiculous amount of redundancy in their story... which makes their story a bit lame..

"So like, I was walking down the street and like it was super hot, like really hot. Then I saw like this weird thing, it was like a big furry thing or something"

A little less "like" a little less metaphor.

"It was pretty hot, I was walking down the street and was shocked to see a bear!"

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.

The Elements of Style by William Strunk Jr. (4th edition) helped a lot. (Note: English is my second language.)

Keep a journal where you write out any ideas you have (about anything). It allows you too audit yourself in real time and makes it harder to hand wave.

In a nutshell...read Zinsser's On Writing Well! So much great advice in it.

Also keeping a diary for 25 years helped me, I think. And reading a lot of great (non-fiction prose) writers: e.g. GK Chesterton, Santayana, Bertrand Russell, RL Stevenson, William James, Emerson, Hazlitt, etc.

Everybody here is focusing on the writing part of the equation but that is not the most important one.

Expressing a thought is just the last step of communication.

Only organized and correctly structured thoughts can be expressed in a clear way.

If you can’t communicate well it is an indication that you are not thinking as well as you think you are, because if you were, you wouldn’t be having problems.

It is fair to say that most people nowadays still don’t know how to write or read. Illiteracy is still a huge problem in the whole world. They might know how to write a word but they can’t explain what the word is supposed to mean.

I see that everyday. My boss will write that “X team member needs to perform at a higher level”, but can’t, for the love of God, provide a specific example or direction as to what that means.

I’m pretty sure she thinks she knows in her head what it means. The problems is she doesn’t. If she knew she would be able to clearly communicate what her expectations are and how X member is not meeting them.

My recommendation is to stop thinking about how to improve the output of your thought process and focus on improving the content.

All great presenters will work months on prepping the message that they want to convey. Every word will be carefully selected because every word has a different specific meaning. That’s why we think people are great at writing or speaking. They are great at that as well, but above all else they are great thinkers.

I've learned a lot by watching keynote speakers, or TED talks. The delivery of some of the speakers is exceptional on how they tie an idea together.

Read books of different authors on different topics. Try to be acknowledged in many themes.

Study copywriting.

I always try to give good advice.