You have to start not to give a damn about whether or not you'll get blown out so you'll stop panicking. I find the trick to that is to be yourself. Like completely yourself. Don't make up stories that aren't true, don't do anything extra to impress someone, etc.
Most of all, and this one is important, don't change the way you feel deep on the inside. For example, if you're a nice social fellow who can talk to anyone, don't push that aside to try and feel like you're a sexy, suave man. If you're not being completely yourself, not only will women notice and their respect for you lower, you also won't pass sh1t tests and blowouts. If you're being completely yourself, there is no reason to feel ashamed, come up with excuses, or apologize for anything.
Besides, something that comes natural for you is far easier to use and to become better at than something that doesn't, which will give you a lot of headache trying to learn. (I wouldn't say that always goes for learning PUA though, a lot of guys have the traits to pick up women, but just didn't know what they want or need to get rid of some social programming. Though some others do seem to be struggling with it).
Also, when you're approaching a woman, don't think of why she wouldn't want you. Think of why she would want you.