So you have to keep it short and casual. You can do that by being direct just not too direct. Just a one two touch. That basically means this:
Say something (like a coment, joke, guestion...) and if her responce is positive (smiling, chating with you) then you just say: what are you doing later, how bout some coffe?
She will eather say yes (no problem. Just take her number)
no (I have a bf, i cant, maybe next time... Give up)
maybe (some objection like i dont know you. Then you just say: well Im working now, but you seem cool how bout we talk more later

)
That should work. During the day its best to keep it simple, short and casual. Dont let the date youll be going on with her sound like a date, its just a coffe... nothing more.
Later on you can play hard, be sexual and so on.
