Satish Classes

It depends on your current proficiency level and where you desire to be with your English speaking skills. I see it as 3 different levels:

1>If you are already at a basic level and would like to be able to converse with confidence- then you don't necessarily need coaching- as a lot of the language is being able to immerse oneself into the language as in reading English books, listening and watching media in English, surrounding yourself within an English environment as in seeking firends who speak in English etc- in fact even with coaching the above immersion is necessary otherwise speaking fluently is not realistic. 

2>Now if you don't even have a basic knowledge of English then Coaching is essential as it will get you started.

3> If you are able to converse at a reasonably good level and would like to furthur enhance this to almost speaking as a native speaker would- then again you will benefit with coaching as this will speed up the process 

So as you can see for the above- really depends on where you are and where you would like to be.

Good Luck!!!

Fluency improves with confidence, and to gain confidence, you need practice and knowledge.
Knowledge is the simpler of the two as you can get that by simply joining a course.
However, to practice that skill, you will need to place yourself into situations where English is spoken or used extensively. You are forced to comprehend and respond in English- and this will specifically help with confidence and ultimately with fluency.