The number one thing she needs to know is What is selling and what is not! Buying domains is easy, selling is the hard part. The fact that you think the domain is good, doesn't mean that anyone else will think it is good. Turn off your emotions and before you buy, identify who may want the domain then ask your self, why don't they already have it? Being a domain investor is one of the hardest things I've done. The "big profits" that you read about are not the norm. So before she starts, she needs to read all she can about domain investing, then study was is selling (look on Namebio). Then read some more.