Erm to be honest it's hard to put my finger on specifics. I worked a lot on getting comfortable with my own self worth.

I got myself into shape physically which helped a lot. On top of that I shaved my hair off. Although I was never overly ugly or fat before the combination of those 2 things along with a little researched shop reduced my physical insecurities.

For gaining inner confidence I watched a couple of hours of RSD Blueprint. Pretty much what I picked up here was all you need to be is a funny confident assertive guy who does what he wants
So i applied that to myself. There are some aspects of my personality such as my manners, principles, my sense of humour and some of my geeky pastimes that make me who I am, however the way I used to supplicate and work around other people nervously was what let me down.

So I started going out and being more social, more lunches with friends or just lunches in cafe's and social places. I went out between 1 & 3 times a week. I was social myself and sometimes I just watched others interact - you see how other people do things right and wrong and I actually realized that in comparison to the majority of people I'm above average in attractiveness and intelligence, that's all I need. I soon got a feel for how people work socially and start practicing it myself. I worked on my body language, doing things with purpose. I applied the same techniques to my speech, slower and a more assertive style. I stopped asking as many questions and not only did I apply it to my social life but also my work, family etc. As Jaz pointed out, it's not about having game, its about being authentic, confident with who you are as a person, assertive, tactfully honest and extended far beyond picking-up girls.

Now even my closest friends say there is such a big difference from even 1 year ago.