I am a complete noob so these questions might be stupid

:
I was experimenting with some openers last night and I ran into a bit of a problem. Most girls I approached reacted in the way I wanted, but then something unexpected happened.
I approached this girl who was like a HB 8. I approached her in the right manner: I walked over confidently at a slight angle and talked to her over my shoulder.
The thing is, when I tried my opener, she didn't understand me, she said: "What?". When I tried it again she still didn't understand me. At this moment my confidence was already sinking. I didn't know if I had to repeat my opener, or hit her with a neg about her bad hearing or something. I decided to try the opener one more time, but when she still didn't understand me I bailed out.
This was at a party, so there was a lot of noise, but the other girls I talked to could at least understand me.
So I've learned that I should talk more clearly, but my question remains, what do you do when girls don't understand your opener up until the point of utter embarassement? Do you giver her a neg about her hearing? Do you keep repeating your opener? It's hard to remain confident when you have to keep repeating your opener.
Also I have another question:
I also experimented with the same opener on friday and number-closed a girl who was also like a HB 8. So now I got her phone number, but I don't actually know what to do with it. I decided to definitely not call or text message her the day after, but now it's been two days, so I'm thinking I should call her or something.
But what should I text message her or say to her on the phone? Is there like a routine for this? I used to to just text message a girl one day or two days after when I got their phonenumber and just asked if they wanted to go for a drink, but now that I'm into the game that just seems boring. And since I'm trying to go from AFC to PUA, I want to really try to get it right and be confident that I'm not making obvious mistakes.
All advice will be greatly appreciated!