What are the techniques used to improve speaking fluency?

The best technique for improving fluency is practice and imitation.

The basis of language is mimicry--every baby learns to speak by listening to and copying their parents and the adults around them. My suggestion is to find either a children's show or some other program that is designed to teach speaking and to keep practicing until your pronounciation sounds right. There are many such programs online as well.

It may be impossible to completely retrain your vocal chords to speak another language perfectly. You may need to settle for a slight accent; however, if you keep practicing and applying your practice to real-life situations, you will improve.