The candidates appearing for the GRE have no eligibility criteria but they are advised to check if the programmes they wish to apply to, accept GRE scores. You cannot give the GRE if you have already given the exam in the last 21 days. There are no limits on the number of attempts and you have the option of sending your best scores to the Universities for their consideration. Although you cannot send separate section-wise scores as per your preference.
In India, it is necessary to show your passport as proof of identity in order to appear for the GRE. Many people have been denied entry at the test centre for not having their original passport as ID proof. So make sure you have your passport ready before booking a date for GRE. For other countries, do check the ETS ID requirements before booking a date.
Visit the link to register for the GRE. You can book test slots near you based on their availability. Choose a test centre near you after checking its reviews on Google Maps and other similar websites. For example, the preferred testing centre in Mumbai is the Prometric test centre and it has good reviews. A poor test centre environment can affect your performance during the test so choosing a good test centre is important. The booking cost for the test is USD 205 which is approximately Rs 14500/- . You have to use a credit card or an international debit card for the transaction.
The GRE being an easy exam is a myth. There are many brilliant people who do not do well on the test due to any number of reasons and there are some people who ace the test without even trying hard. It is a standardized test which is improved over time by gathering data from previous test-takers.
A good GRE score is also a relative term based on the courses you intend to apply for. For students looking to get into the best Computer Science courses, even a 330 GRE score is not sufficient based on the factors the admission team decides to assign importance to while selecting students. Have a look at the average profiles on the college websites to get an idea in this regard. You can get into a top college with a low GRE score if you excel in other aspects important for the course you apply to.
From the table 1B in the article it is clear that more people get a 165+ score in the Quants section than in the Verbal section.