Tip 1 : Know everything you've prepared in your resume by heart. They only asked me from topics that were included in my resumé.
Tip 2 : Prepare CS theory and Aptitude as well as you can almost 90% applicants are filtered out by the first round.
Tip 3 : Listen to the pre-placement session very carefully and jot out points from there. These points could later be used when the interviewer asks questions like, "why do you wanna join Deloitte"
Tip 4 : Ask questions. The right questions. Not about your interview or the interviewer but the company.

Tip 1 : Your skills and projects are the most important parts of your resumé. Elaborate on the tech stacks used on the project, it's working etc. 
Tip 2 : Briefly explain what you did in your past experience even if it was an internship. Why were you valuable to the organisation what were your contributions.