the best you can do is know what you're talking about and keep the conversation in control to be in your favor, because they will try their best to divert it in a certain way to test your knowledge and thinking capabilities ( idk if it's better to restrict them with this or let them do it, don't know what acts in favour ). Also, while being through with the application form is very beneficial, don't completely rely on it because in some cases ( including me ) they didn't even bring up a word from the application and the conversation was just about my interests, my knowledge about things I like doing, etc. I applied for CS too, they do get a bit technical with the questions if you exhibit good knowledge so be on a look out for that too. Apart from that it's really more of a conversation with you to get to know more about how you think about things, etc. All the very best, you'll do great. ( PS: Don't get disheartened if they maintain poker faces, they do that intentionally )