Hello 

Coaching is for your guidance, they help you with the concepts of certain chapters which you didn't understand during college lectures. It helps you to understand the chapters thoroughly, So if after joining college and not scoring well on semester exams , you can surely go for Coaching. But if you are attending regular classes , going college everyday, concentrating in lectures, then you won't be needing any Coaching centers, so it just depends on you. 

Hope it helps :)

All the best :)