Hi
As I understand from your post, language may not be the problem but organizing your thought process could be your primary problem when it comes to drafting skills.
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 - Daily Blog
Www.poweract.blogspot.com - Weekly Blog
Your comments on the blogs and the writing style will also be much appreciated.
Hope the ideas expressed will you a good starting point for you to prepare, practice and perform well.
If you do a search in Citehr you will find posts related to sample letters, memo's etc. However you will have to adapt the same to meet your spefici requirements.
Regards and Best Wishes