I'm not great at this kind of thing but I'll try my best:
I'd start with meditating to get better focus. Then when you dream about her, take notice of your surroundings, accent - anything that could give away a location.
I think crying may also help, if you try to look deep within yourself to try and find this mystery woman.
Finally, I would pray to whatever deity/god/goddess that you worship that has to do with love, and ask them for guidance on leading you to her.