Rajeshwar u can follow (un academy) in youtube for online coaching classes

Well you can join any coaching institutes like Allen, Bansal, Aakash etc. But It totally depends on how you manage your time to study apart from coaching. Competetions see your knowledge in that subject, coaching help you to build your concept, but you have to do your best to get the result. 
Some of Good coaching Institutes are: Aakash(Available in most Cities), Allen, Resonance, Bansal etc.