You could also tell her to try and drop a couple of items, such as a hat or glove, better still throw them over a garden fence to where the perp can't easily retrieve them, especially something that could identify her, at the same time as shouting to attract attention, in the hope that someone will notice the incident and report them.
That way there's a chance the police will find out promptly, and then know when and where she was snatched, which helps with searching CCTV footage and finding witnesses.
P.S. Also, even if she hasn't been able to do anything like that, she could lie to the perp by saying she has.
I'd also point out that the best way is to be prepared, e.g. carry a sound alarm and a mobile phone that reports location to agreed phones on demand (I think one can get these now), tell people where she is going, and obviously take steps to avoid danger in the first place.
Edit: Oh and mention that not all abductors are guys. Women are sometimes involved, believe it or not, because they don't seem so threatening. Also, they aren't always stereotypical DOMs in a raincoat. It's more likely to be some maladjusted teenage boy.