She certainly has talent, which should be encouraged!
Lisa Ann Dawkins (linked by @HotPatootiebootie) works in dry media - coloured pencil/pastel pencil and pastels, which are media used by many animal portraitists, as they render life-like fur beautifully. I’m not very keen on acrylics as it can appear a little harsh and blocky.
Backgrounds should always be neutral in colour, so as not to clash with decor (unless the commissioner has other ideas).
There are many animal portraitists with YouTube demos, and she could have a look at some of those for ideas.
I did think about doing pet portraits years ago, but decided against it at the time, due to other constraints on my time, but I haven’t painted for quite a few years. I also prefer the dry media I mentioned above, mainly pastels and pastel pencils, but they are expensive to buy initially, for good Artist quality materials.
As always with art, it’s practice, practice, practice!
I’ve attached a portrait I did about 15 years ago, of my friend’s Westie, given as a present. I used pastel pencils on velour paper which has a velvety flocked surface and is rather unforgiving to correct errors on, if I were to do it again I would use a newer surface called Pastelmat, which seems very popular with pastel artists these days.