Taken from Yahoo! Answers
~To be a poised lady you should understand the importance of etiquette. Showing respect to others through good manners is the mark of a lady.
~Use good posture.
~Speak gently and without vulgarity, smile, always offer to help others, and call as little attention to yourself as possible.
~A woman who possesses poise and grace will attract attention naturally.
~Always take extra time when getting ready to make sure that your clothes are pressed and free of lint, no undergarments are showing, hem length is appropriate, and especially that your shoes are in good condition.
~Never wear too much fragrance.
~Wear attractive makeup, nothing harsh or bright.
~Have fun! Ladies know when it is appropriate to laugh and enjoy themselves.
~Always be kind to others no matter what. There will always be people who are rude, but a poised lady knows how to handle herself in those situations without being rude herself.
~And most importantly have CONFIDENCE!!! Pride in oneself is the ultimate factor in poise. Be proud of who you are, and the rest will come naturally!
An excellent resource is Amy Vanderbilt’s Complete Guide to Etiquette as well as How To Be A Lady by Candice Simpson.