I think an opener is ment to just start a convo. Instead of stressing over what to say just try anything. Through my experence, Once the convo starts girls won't remember how u opened them.
If your afraid of rejection try this: Its called the "crash and burn strategy" from the stylelife challenge book. What you do is go up to a girl and ask them if they can blow u out. that you need to get blown out. they will most likely wonder what ur talkin about and then you explain, "thats when a guy comes by and your in some mood, so your totally rude and don't want to talk, and you tell the guy to fuck off. Most likely they will interupt you and tell you that they are not rude... This helped me get over my fear of rejection. From this you can get into a convo about your fears of talking to girls that you like and just be real. Don't worry about the outcome, just try to build experence. When you build experence, you build confidence. Once you have confidence you start realizing how easy things really are. I hope this helps you out.