I recommend taking Pierrot advice. Practice makes perfect. You have to get over what is called Approach Anxiety. That is the actual PUA term for it. I think you should look into getting "The Rules of the game" by Neil Strauss (Style). There is an entire excerpt about overcoming this. It is also loaded with a lot of other valuable info, such as canned openers, how to create a false time constraint, how to implement a root to your opener and much more. the book is only like 15 bucks.
I think both Onyx and Noname are right in their own sense. There are definite ways to open that will help you build attraction, hook girls, and then be able to start build comfort and finally close.
I also recommend the Mystery Method, another book that should give you more great info on how to do this.
All the info above that I have listed is phenominal, but as Pierrot said YOU MUST make a point to TRY AGAIN and AGAIN. The great MPua's say that they have hundreds or even thousands of rejections before they started being extremely successful.
They also say that there is no such thing as rejection, it is all just feedback. How could you have approached differently? What can you change with the next approach?
Also you cannot blame a blown opportunity on the girl. It's on us as PUA's. We have to be open to constructive criticism in order to correct it.
I suggest you read some material to familiarize yourself with actual methods for approach. Get a good consistent wingman, and go out and Sarge. Lots of girls, different girls, and numerous girls. Try different openers on different types of girls and track your results to improve.
Do the stylelife challenges. Takes 30 days and it will teach you tons. Read the Mystery Method, which is who Style learned his roots from and learn how to Open, build comfort and then sex close in a 7-10 hour period(this can be over the course of days).
Anyway, Good luck and keep us all posted on your success. If you have any questions for me, my Mail box is always open. LOL