Congratulations on your interview! You got some great advice and resources here already, so I'll just add my extra two cents: the key is practice - both for the case and behavioral portion.
I would recommend starting case practice by reviewing some common case books and frameworks (e.g., Case In Point, Case Interview Secrets). It can also be helpful at this stage to listen to some experienced casers solving a case - you can find some on consulting companies' websites, or just do a search on YouTube.
Once you understand more or less what solving a case involves, jump into live case practices! You can find case partners and coaches who can offer expert feedback here on PrepLounge, but you can also practice with friends or family back home. Generally speaking, this will be the bulk of your prep. Notice which parts of the case are naturally more challenging for you, and devote more time to those.
Finally, don't neglect the behavioral component of the interview. Look up frequently asked behavioral questions (there are great resources on PrepLounge about this too), prepare some answers, and be sure to practice them.
Best of luck!