As I understand from your post, both English language skills as well as organizing your thought process forms part of your problem.
To improve your English language skills I strongly suggest that your read extensively, speak in English as often as possible and of course attempt to write in English too. To force yourself to speak, try and make more friends who speak in English. Don't be embarrassed or hurt if they occasionally smirk or criticize your language. On the contrary learn from them when they correct you and note the progress you make.
When reading, look up the meaning of new words. Improve your vocabulary by finding synonyms of words and using it. Ensure you have a Dictionary as well as a Thesaurus and use both these extensively. Don't be shy to find out people who have a good command of English and seek their help when you want clarifications on help.
The next problem of writing must be tackled differently. In this context it is important to understand that some people are naturally gifted with the ability to write and express well, just as some others can articulate and speak well while others have an extraordinary gift of sketching and painting or are stronger in Maths and Science.
Does this mean that there is no hope for others? It is just that others have to understand their own style, adapt new techniques and work hard. So by posting your problem you have initiated the first step of seeking out new techniques and I am sure you are prepared to work hard too.
To organize your thoughts, read up on the Tony Buzzan Style of Mind Mapping which is a well known technique. If possible attend a workshop on that style. However I have neither attended such a program nor met any one who has undergone such a workshop so you have to check out on effectiveness and suitability of the same for you.
I have developed my own style and the key is to begin with a simple starting point which could be in the form of a subject line (as you would do in a letter) so that the crux of the writing is clear first. This would give you the fulcrum around which to outline your points. With this fulcrum in place, make a list of collaborating, competing, supporting and dysfunctional ideas. Each of these could possibly be the sub fulcrum of each paragraph or set of paragraphs. They can also act as sub ideas and sub titles. Now add meat to the skeleton using sentences peppered with action words, adjectives and the right tone.
To have an idea of my style of writing do visit my Inspirational and Motivational Blogs listed below
www.actspot.wordpress.com - Over 1,08,000 views and 685 followers
www.poweract.blogspot.com - Over 33,000 views and 180 followers
Your comments on the blogs and the writing style will also be much appreciated.
Hope the ideas expressed will give you a good starting point for you to prepare, practice and perform well.
Regards and Best Wishes
If you want to speak good English, speak with someone who can listen to you, tell you your mistakes and help you correct them.
You could also checkout BodhiSutra for a Live Spoken English training course on phone.