This might be a clunky question, but if you are interested in multiple girls that you've met before; how do you decide who to approach first?

This applies to me at my work. (Work is my primary source of social activities) I am into too many girls there to keep track of, and I wanna know who to muster up the courage to approach first; because I was raised to be strictly monogamous, and I can't be that way if I do get a girl, and I'm still looking to get with other girls at the same time.