One big tip while flirting with a girl is to give her due space. You might feel that the moment is opportune to ask for her phone number. But if you do ask and she refuses do not at any cost force her into giving it. Men who are too forceful on a woman are big turnoffs for the latter. Especially, the modern woman does not want her man to dictate terms and coerce her into doing things. So give her the space she desires and in return you will also get the space and time you want. After all, when the respect is mutual, the relationship is bound to go forward.