9 times out of 10, I'll be gaming a chick and everything is going fine. She's leaning in to talk to me, playing with her hair, giving me eye contact, etc., etc. I'll get her phone number and contact her a couple days later and it goes absolutely nowhere. The problem is that she is not truly excited to go out of her way to see me... I become low priority. It's almost as if I've been forgotten. I'm aware that I should become scarce and not readily available, but what's a good way to do this? Should I be setting up the Day 2 as I'm getting the phone number? If I do this, where's the guarantee that she won't flake? If she does flake, what do I do then?

-Stig

In my personal experience, having a funny/sexual based text conversation after getting her number makes you memorable. Girls for some reason feel comfortable around me after texting for a short time. Go figure.

When you get the phone number, do you have a reason other than wanting to hang out sometime? If you don't, that could be one of your issues. To be honest, girls feel a lot more invested when they have already agreed to do something particular like go to a ceartain Sushi spot, rather than something as vague as hang out.
I think contacting a girl a couple of days after getting her number is shitty. It makes it easy to forget you. Think of this way, if a girl gives her number out to five other guys a week- that's five other guy she's met. Chances are, she's going to forget you- unless you make yourself known. You need to text her that night, or the next day. This reinforces you into her memory. I don't believe this, wait a few days to text a girl thing- if you don't it'll come off as needy and is a DLV. Everybody texts all the time. It takes one second, and it's not like you're trying to call her. Use texting to transition into a phone call, and then set up a date.
Also- qualification. You need to give girls reasons why you like them other than their physical looks. When you get a phone number without qualification- and you go to set up a date- chances are the girl is going to wonder why you like her. "Why is he calling me? Why does he like me? Oh, it must be because I have a vagina. "
When you've properly gave the girl an oppurtunity to qualify herself to you she'll ask that same question, but her answer will be drastically different. It'll be something like, "He's calling me because we both like sushi, or that I'm going to school to be a Vet and he likes animals too."
Hope that helps.