"Most Indian student visa applicants in India will receive the visa on their first try, so we encourage students to not focus on denials.  There are a number of reasons why a visa could be denied, most common being that an applicant was not able to demonstrate their intention to return to India," says Spokesperson at the US Consulate General Hyderabad

Mismatch of academic background to the degree to which admission is sought, which is to say that an applicant for a postgraduate (PG) course, should possess a undergraduate (UG) background. 

Another concern is if the aspirant's academic profile is strong, but they enroll in a Tier III university and vice versa.

Failure to have the required minimum sum in their bank accounts. Even if they are receiving scholarships or are going for loans, it is essential to have a minimum bank balance to reassure the consulate of the ability to meet financial needs while staying in the US. 

A few students fail the interview if they lack communication skills or become too nervous to coherently answer all questions.