This is one of my favorite sites:http://www.knittychick.com/freebiepatterns.htm
When I started making bags, I measured the ones I own and decided from that what size I'd like to have. Of course, learning to guage is something we all learn in our own way and she'll get that. Most importantly, DO THOSE SWATCHES and felt them. It is well worth the effort.
Another thing I found when knitting in the round was the first stitch where you join another color is tricky. If not lined up, this will be an obvious thing once it is felted. I eventually learned to weave in the ends of the two colors by knitting them into the first row on the point of change. It's kinda like intarsia and done the same way. I double the new color, knitting the excess until it's too small to knit and loop over the previous color before each new stitch.
Okay, I'm rambling..... I have other sites but this one will be a good one for her to "shop". I'm still making mistakes and learning but will help anyway I can. Mary