I have been playing since 2007, and I still don't have a firm answer to give you on how nerves work. I think everyone has their own way of handling pressure, but it can be just as dangerous as the patterns if you let it get to you. For me at least, my regular way of handling nerves is to try not caring too much about the results of a run. If you improve, and keep trying, then eventually the result you want will come to you. Thinking too much about the run at hand will just distract you from what you need to be doing in that moment. Or so I tell myself at least, until I screw up and then it becomes a struggle to recover.
As hokey as it sounds though, this is the kind of thing you have to figure out for yourself. Think of it like martial arts: Cultivating a state of mind is just as, if not more important than raw technique.