An approach to a girl that you like is watching what she is doing while a jerk is talking to her. While sitting near her table you could go across an opportunity like this to seduce a woman. Do not waste this moment! Smile her and if you have a good acceptance you will have won the first step on the seduction way.
Make sure, before you make eye contact with the girl you want to seduce, you give a good first impression, of a confident man. If she sees that you're nervous, and lost, you will lose seduction. Do not look apart, you have to keep looking at her, but evidently do not be a maniac insistent. Do it in a relaxed way and smile but not exaggeratedly.
Everything has to be natural. She must not be intimidated by your insistent look at her. You will know you lost your opportunity if she departs and looks surprised by your gaze.
Another good technique while you are in this game is ignoring her a moment and turn to the table and to continue to chat with your friends. If she is interested in you, she will bring you back her eyes to you and it will be your chance of seducing her.