I always tell the competitors I speak with to take advantage of every second they're on stage - but especially for the ladies of Bikini. Lacking mandatory poses, and coupled with the huge numbers of competitors that get on stage, these ladies must really make every second count.
1. Shift your hair on back shots to show your detail
2. Smile. SMILE. SMILE!
3. Show off your Glutes, never relax them
4. Never relax your midsection
5. Move gracefully (practice transitioning)
6. SASHAY - ON - & - OFF stage. Walk with rhythm, style!
I personally believe that for Bikini, a large amount of your placing deals with the interaction and reaction you get from the audience (similarly with Men's Physique). The judges realize that that Bikini is a cash cow & I think they want the fans to leave happy. I don't have proof of this, except for the fact that I've never seen a crowd-pleaser finish last or down in the second half.
Make every second count. Just because you're not up, doesn't mean you're not being watched. There's a sea of beautiful women - STAND OUT!