Could Some seniors from Thapar University who bagged placements share what juniors could do to gain good placements?

The seniors at Thapar University are really helpful and cooperative. Here are some things which might answer your question. 

• Finish CLRS “Introduction to Algorithms” textbook in your first year. This is the most important rule.
• Start participating in programming contests, such as TopCoder SRMs, right from your first year. 
• Make sure you are a part of some cool projects in college. 
• Build your GitHub profile.
• Engage in startup culture. Try to create jobs rather than looking for one.
• Visit HackerNews (HN) every day. You'll learn great things and see cool projects worldwide.
• Learn everything you can about Machine learning and Deep learning. 
• Play hard with CNNs, RNNs, GANs, etc. Try to create some cool projects around ML.
• Engage in some real research work, better if under your professors and publish papers.
• Study for placements during holidays.
• Read “Cracking the coding interview”. Do placement questions from the career cup for your dream companies.
• If you dream of Google, prepare hard for Google's APAC test. It is like another JEE. 
• Keep eye on reputed international internships and grab one if you can. Discuss more on this with your professors.

Lastly, it is suggested that you keep your body and mind fit. You need to stay healthy and think clearly during the placement process.