Hi Aspirant,
You can apply through various ways.
Firstly,try to get a good score in your boards.
Then,having good results in graduation helps.You do not need remarkable results,you just need consistent results.Also,if you have any achievement in any olympiad or something similar,it helps.Having letters of recommendation and a very sound statement of purpose is essential.Also,make sure that your application procedure is complete and correct.
Remember this,where most students make a mistake is that they try to use fancy words and often try to exaggerate.It simply is not required.Write whatever is true and in simple words.
Also,it's important to mention that a good GRE score can really be very helpful.Similarly,a work ex can also matter.
Also,focus on the quality of knowledge you have and not on the quantity.
Hope this helps.