I have fine wavy/ whurly (2c) hair. I would definitely agree with protein-containing products for her fine hair. Adding protein into my regimen is the #1 thing that has helped me on my curly journey.
For gel, I would recommend scrunching it in her hair. At least for me, raking styling products through my hair is a disaster, I have to scrunch them in. I'm a fan of applying styling products / gels to dripping wet hair, and then really scrunching them in well (scrunch and pump, or just lots of scrunching!). That gets my waves and curls going. AIF tends to give me frizz as the day goes on, and lots of it if I use it multiple days in a row (I blame the polyquat in it). Just something to be aware of, lots of people love it though. BRHG on the other hand, I can use day after day and it's fantastic for me.
She could definitely play around with diffusing as well, since it helps set the gel cast around the curls without them being weighed down by just dripping dry. With that said, I personally almost always air dry for convenience but my hair definitely has less volume than if I diffuse even for a few minutes.