Next you ask someone out, after determining that they are single, only to find out that "I'm not looking for a boyfriend right now." Now you know to determine that people are looking for boyfriends before asking them out.

"I'm not looking right now" might as well be an excuse, what she really wants to say may be "You are not really interesting enough for me to consider you as a potential boyfriend." In that case the correct answer would be to become more interesting, and here you have one of the basic ideas of pick up.