Welcome Entropy !
Since as I understood you are stuck on the IOIs and can't really figure out when to kiss or number close with the lady,I'll give you a summary of short tips that you can find all across this site
First of all,when you approach someone,don't instantly raise the alarm that you want to approach her in a sexual manner.Small talk,small talk and small talk.In The Game there is a whole IOI thing in the end of one of the first chapters,but the biggest IOI is this;the girl is still talking to you and she tries to keep the convo going.
Plays with hair,stares in your eyes/lips,has turned her body to face you,seems impressed etc.
If you feel you cant fclose the girl or that is not your aim at the given moment,and you want her phone,just ask for it.In order to make sure she has given you the right phone,read it back to her while changing one of the digits and seeing if she will tell you you did something wrong.(dont get angry if she gave you a fake number,just be polite and close the set).
If you want to kiss close the girl,dont do it in front of her friends,cause even if she likes you,she may feel unconfortable.If you ask her to follow you somewhere and she does,that's an IOI by itself,so kissclosing should be a piece of cake
Hope I helped,I'm here to talk about anything If you need it !