Okay need an advice from someone who is good with words or anyone else that has a good idea about this

If you`ve been talking with a girl for sometime and you know she is quite shy and introverted but does make eye-contact and smile and if you ask her out and she just blushes or smiles and stays speechless... with what should you follow?? I need this because I think it can actually happen to me pretty soon. I need something good to say then to fire my chances up and open her mouth.

Also if she says no.. do you continue talking like you didn`t ask? Because I see her many times.