very important part of kebaya round is " the walk". Try to practice walk 10m to one point, then turn around, walk back to starting point. But smile, relax, must have good posture (ask a friend who is good at pilates to help you see), smile smile smile!
Even if it feels scary with the spotlight in your face and eyes, you still must look at the interviewer.. smileeeee and say "thank you very much!!" As if you had really enjoyed every single process in the kebaya round...

*P.S. As for the red nails, it up to you lah, my personal experience is, it helped me to stand out. Out of 10 girls in the first round, the interviewer asked me a personal question. "Why i painted my nails red" I gave a small laugh.. hmmm... told him the truth that an auntie at SQ advised me that, and i had to rush it at 3am!!!(when the walk in was at 9am) Both of them smile, laugh back abit, and nodded their head.
some little things, IF you do it well and nicely, will allow you to stand out from the next girl. Find out what works for you.
(my philosophy when i went for my walk in is that i will look ready for the job already, so i groomed myself to look as alike as SQ girl.. put on some makeup..*lipstick* hair super neat etc.. hehe..
Most important is your personality lah. Imagine the day of the interview is the happiest day of your life and everyone you meet there are long lost friends you havent met in a super long time then just keep smiling and chatting with one another, be in a happy mood.. haha.. thats what happened for my group, and we helped calm each others nerves