Rhea, 

Like you know, nobody would be able to guide you better than your own self. Firstly you need to evaluate yourself that what suits you more. The coaching classes or home studies. If you are comfortable enough with your self studies, plan a strategy and refer to online lectures and mocks.

Secondly if you feel you need guidance from coaching and there are subjects which you feel need to be worked upon join your coaching accordingly.

Thank you 

See there is no such rule that coaching for a year do or don't Or coaching from a particular institute gurantees an admission.

There are instances where students right from foundation are studying in caoaching centres, but dont get a seat whereas with no coaching some does. 

Now, coming to your main question yes one year of proper study with proper guidance and mock tests is enough for getting a good rank.

Yes sure...Provided if you are very thorough with the concept and the objective style of practicing the questions.

There are students who work hard and smart and they do excel in the result.