Probably too late, but I use photoshop from the start and my advice is to try different styles of graphic and genre to find her own style and the best genre she can make... ^^

Thank you everyone for your advice! I ended up showing her this post! You guys are really super nice and lovely for helping! <3

Also tell her to look around YouTube for tutorials on how to download it for free. I have downloaded Adobe Photoshop CS6 for free like that :)

I used Photoshop from the beginning. It takes practice to get better at working with, but its dedinitely the best program for graphic art.

Currently using Photoshop but I used GIMP when I first started.

I just went straight and get started with Photoshop, but just like 500sunny500 said, most people do get started with GIMP as it is free.

@500sunny500 thank you! I'll let her know~

If you can, get Photoshop.
If you can't, then I highly recommend GIMP. GIMP is free and similar to Photoshop (with other exceptions, of course). However, GIMP is a good place to start if you're looking for a free software that's similar to Photoshop. I know that along with Photoshop, there are GIMP tutorials on this site.