This may sound a little difficult but when you get down to its really not. Let me start by saying what will not impress a girl. First and foremost you trying to be something that you are not. If you put on some false fašade then she will see right through it. If you BS like a snake oil sales man then if you really like her and want to develop a long term relationship your BS will come back to haunt you.
By the way impressing a girl is never going to be 100%. If you are true to yourself and are charming and decent you just may run into somebody who is having a bad day or just is grumpy in general. So don't get all negative if a girl is not taking a fancy to you.
Basically to impress a girl get off the stage. You do not need to be an actor. Don't try and impress just be yourself. If the roles were reversed how would you like if one after another guys came up and try and put the works on you with flashy clothes, cheesy chat up lines and made up stories. Actually it would probably be a little bit comical.
If you really like a girl then the best way to impress her is just to go up and say Hi. Do not get personal off the bat. Try and bring something up in conversation that is relative to your surroundings. Look her in the eyes and relax. Poke a little fun at yourself then if the opportunity arises poke fun at her. A little humor goes a long way. Please just do not try and impress her. Stand up straight and be who you are.
Guy's if you are serious about getting the girl of your dreams then you need to seriously work on solid techniques to achieve your goal. If you know what a girl is thinking it is far easier to approach her. If You want to learn the tested psychological secrets of the female mind given to you by a woman because after all only a woman truly knows what a woman wants, then select one of the following links... You can learn this and a lot more.
Learn what you NEED to know before approaching a woman.