AoA
First of all , u better realize it that it isn't a matter of a while, it will take at least 3 to 4 months (if u take it on urself) otherwise
can end in undesired results.
ok, now the question is HOW to do it?
Key points u need to remember all the time,
A good reader is a good writer....A good listener is a good speaker
well if i can give u some really helpful tips, then these are..
1. Start Writing 2-3 paras about your past,present & future experiences, (if u think this is silly, then don't worry, it isn't silly
), Trust me it will improve ur writing skill, and your speaking skill too...
Examples ..Your experience regarding a trip, college party, outing, or any specific DESCRIPTION also, Like Describing yourself as a CHILD...
and continue this to the present,,and then future,,,
just do three examples each for three phases ,Past,present,future
then u will be able to PIN POINT your WEAKNESSES, and this is the moment when u will start improving..
I hope,,i didnt made it a Mess,,,tried to clear the topic, as much as i could,,,hope it would be helpful