Good posture is imperative for any form of dance. Tops tips for improving your posture are:

Ground yourself - imagine your feet are sticking to the floor.
Center yourself over the balls of your feet.
Imagine a piece of string is attached to and pulling at the crown of your head.
Shoulders down, with shoulder blades back
Lift your abdominal wall
Lift your chest
Relax your shoulders
Relax your jaw
Drop your tailbone toward the floor, rather than tucking your tail.
Eyeline and focus

Most people have postural problems to some extent. Unfortunately an imbalance of posture may not affect function in an obvious way initially and so go unnoticed. The time comes however when it starts to manifest itself in contorted movements and a distorted posture. Quite often this is brought about by developing a visual image of how a step or line should be achieved but not the correct technique to achieve it. This will establish a faulty muscle pattern that will lead to strain distortion and difficulty in performing the step.
The most important thing to remember is that good postural alignment, centre and inner strength are vital when performing whatever standard we are, and observation of the central point of balance is the only course for a successful performance whatever the subject.