I'm still pretty new to the whole pick up thing, and I haven't really put my all into it yet, but one thing I did that had a very clear positive impact on me was reading a few books on body language.

First of all, being able to interpret body language puts your anxiety at ease like no other. One of my biggest obstacles in pick up was constantly worrying about how the other person felt about the conversation. Being able to read there body language gives you an idea as to how they're feeling, and if you're really attentive you can figure out weather or not you're the one making them feel that way.

Another thing knowing body language does for you is that you can purposely use it to change the way you behave. The body will go along with how you are feeling, but more importantly, your feelings will go along with your body as well. Using more confident body language will make you a more confident person.

It's also super useful for flirting. I've always had a problem with openly flirting with girls I was interested in. I just couldn't bring myself to say anything flirty. I realized that I was never going to get anywhere if I didn't let the them know I was interested though. Now that I understand body language better, that's what I use to flirt with them. I purposely tell them I'm interested without having to say a word about it. With body language you don't have to worry about leading the conversation anywhere. You could be talking about washing dishes or some other boring as fuck topic and still be telling them "I'm interested in you"