This is a video from Simple Pickup showing the same principles as Tyler mentions above. It also shows the value of persistence by overcoming the shit tests from the girls. Shit tests are ways girls 'screen' out weak guys. They often do not know they are doing this.
I learnt from Simple Pickup that you can get away with anything when hitting on girls, as long as you hold the frame (underlying meaning of the interaction) and are dominant.
This video from Simple Pickup shows that limiting beliefs could play a huge part if you let them, however despite being in wheelchairs, these guys successfully get girls numbers, and by the sound of it, they are genuine.
Another video by the same guys, portrays that confidence is HUGELY important when it comes to meeting women. Breaking tonality, good body language (standing upright), powerful eye contact, increases attraction. Basically, it demonstrates to the girl that you have value. It is masculine and polarising to them.
Self-esteem is hugely important for achieving great results in life, believing you are good enough and making you are happy all the time. Ego, on the other hand, is your identity. If you believe you are the pimp or you are this and that, everything you do will be filtered through this. This is where nervousness can occur, because your identity is under threat. Self esteem is about common humanity - you do not compare yourself with others, whilst ego is about separation and difference.