Most men get rejected a LOT. Your "pick up artist" friend is only successful with very insecure women who think they deserve to be treated like shit. Do you really want a doormat for a gf?? Someone who has no real self respect or self worth? If you want a strong, independent, intelligent, kind, decent woman who knows what shes worth then don't change.
Most women don't want to be treated badly so if you start doing that you will end up worse off. Maybe hold off a little in the early stages of being too sensitive/emotional/romantic. Women love that in general but not too soon.
We like men who are a combination of assertive, confident, strong, protective and manly whilst also being genuine, decent, honest, affectionate and loving.