Help approaching girls

I know this is a pretty common question that a lot of guys ask, but I feel that I need some direct advice instead of a generic website's suggestions. I am a 16, almost 17 year old boy, and one thing I've never really had is a relationship. I'm talking about the type of relationship that others have (e.g. Spending a lot of time w/ eachother, going to dances, going on dates, etc.). I technically have been in 2 relationships when I was 15, ine that lasted 1 week, and the other for about 2-3 months in secret that ended pretty badly; but both of those were more long-distance (what teenagers consider long-distance), and I found myself more sad in those relationships because it was a constant feeling of missing my girlfriends. I met these 2 girls through my mom, and some of her co-workers daughters I hit it off with, but I never had to approach them because it was done for me. Even before I met them though, I had issues with approaching girls. I am fine once the introduction is out of the way, but I can't introduce myself. I get extremely nervous when I think about it in the presence of the person I want to approach. My stomach gets butterflies (except really bad), I dwell on what could go wrong, and then I back out of the approach. My friends talk about how they get all of these girls numbers, and most of them are in relationships, and to be honest, I get jealous of them. I have watched numerous videos on how to approach girls, and read numerous articles on it, and none of them have helped me, I still experience the same issues. So my question is, is what are good tips and tricks to approaching girls? What do I say when I approach them? I just feel that some real answers from real people will be more helpful and have much more of an impact on me and my mindset than a video or a website will.

get this book called The game.