Open trading account 
Well it's been a while since I've seen my girlfriends so I was waiting for my travel back home to Latvia to make this small research.
It's a tricky question because I was always good in friendship with boys, but I'm not always having a common understanding with ladies.
And there are several reasons for that. First - I hate talking gossips, but all girls do that. My last 2 day research showed me that I'm also talking about gossips as soon as my friends start talking about this. It's like a poison - you know it's bad and actually not very useful, but you just can't stop if someone started it.
The second reason - I hate hate hate talking about clothes and shopping. That's the most boring subject to talk about ever! But the same - all my girls start talking about it and then I have to pretend I'm into it and have a small conversation about it. During that time I completely feel my brains are shrinking!
And the most important reason is that after such talks I rarely feel myself satisfied with communication.
So my formula for positive and fertile communication with my girlfriends is:
Talk about last personal news just to be ware what is happening
Plus
Share my last thought about this world imperfection
Plus
Talk about new world developments, technologies and possibilities of the human
Plus
Share my latest theories and philosophical thoughts and ask to share with me hers
Minus
Avoid gossip subject or only reply to them once and start new subject
Minus
Avoid shopping conversations as much as you can
Minus
Avoid girls who cannot do all of the above and start friendship with intelligent boys