A simple first step is pick a focus fabric and then use the color registrations in the selvage to work with for coordinating fabrics. I have taught a few starters who just got lost in Colorland ... and this was very useful to them .
Another method is to take a Home dec magazine and ask which photo she likes the most ... identify the colors and scales and how the designer used them in what proportion. Maybe give her a subsription to a quilt magazine.
Just a note.. does he comment about how beautiful other quilters works are .... or does she really like what she picks out when the project is completed?
I do feel your pain ... and Ihave been where you are ... had a close friend that was ... challenged. She knows there is an issue because she asked for your help.