I would plunge in and start reading some of the books that others have recommended in another thread if you don't have another gifted child you've already done the research for in the past. When I was advised my youngest was gifted late last year, I gobbled up 10 books on giftedness over the summer months so I could feel prepared to advocate.
Just know that sometimes kids are really good at hiding their abilities. Ask her what interests her and go above and beyond to provide her enrichment opportunities outside of school.
My 12 yo DD is also gifted and her math scores on the Stanford 10 blew me away. She had somehow not gotten discovered through the normal screening process and we asked for an evaluation for her ourselves. I honestly expected my son's scores to be way higher than hers, but they weren't. She hid it well (plus, if you have a gifted kid as a first child, your perception of what a "normal" kid is somewhat skewed. You assume your kid is normal, when they are really not!) Good luck!
