Hi,
Spoken English is no Rocket Science if you start treating it as your mother tongue.
A child learns the mother tongue at first before learning/knowing national or business language;so as you. What was the mantra at that time when u learnt your mother tongue.
Easy to guesss, " Environment".
You need to create a complete english predominant environment around you. Books , newspapers, tv channels, videos, telephone chat, sms, your meal iteneary... friends, infact everything.
You might be silent of shyness initially, but tahts normal, as when you were learning your mother tongue also, you were passive participant. But you improved, and hence you will again.
Be firm in observing the new environment around you, it will help you to learn the practical application of English with correct usage. Once comfortable, consult theory on grammar and other documents for knowledge correction. and then again rehearse..
You will start living it one day!!!
Trust yourself and go ahead!!
All the best.