I think one of the number one problems so many straight guys have in their relationship to the opposite sex is their preoccupation with women as sex objects.
If you want to be a casanova then don't approach women from the first second you meet them as a potential mates. Treat them as people.
I am a gay man. 60% of my friends are straight men, another 35% are straight or lesbian women, and maybe 5% at most are gay. The reason for this is that I am a person to the first 95% of those people. For the gay guys, 90% of them can't seem to get beyond my pecs and arse, so it creates friction in our interactions.
So many of my straight male friends are as jealous as hell about my ability to get on with women. I'll be in a nightclub with a group of straight guys. They'll be in a group together and i'll be off with a group of maybe 5 or more of the sexiest women in the place crowded around me chatting away.
The straight guys tell me that i'd be a legend if I was straight. But they are wrong. The reason the women are crowded around me is because I treat them as people. They don't feel they have to be on guard with me all the time. Most of the time they don't even know I am gay. These women just feel a sense of comfort with me because I don't view them as sex objects, which otherwise would affect my whole demeanour towards them.
It is no coincidence that so many women complain that the best guys are either married or gay. Why don't you strike up an acquaintance with a gay guy (assuming you are secure enough in your own sexuality to do this). Observe the way he behaves towards women. If you learn from this then you may discover a positive transformation in your own relationships.
Just my 2 cents.