"Every breeder starts somewhere" seems to have become the mantra to breed animals from any joe schmoe that can stick some males and females together. Honestly, yes, every breeder starts somewhere. You start getting hounded on when you're given great advice on how we ALL wish we had started and you just do it your way because you feel you're ready to start.
I don't know Mary and I've never heard of her. I highly doubt she breeds high quality animals with great show potential and stellar lines. Every great once in a while it can happen, but 99% of the time you get poor quality animals from backyard breeders. A backyard breeder is anyone that produces "healthy" animals for "fun" and doesn't attend shows or care about producing quality.
What colors do you hope to achieve? What qualities do you think each of the chinchillas' has that compliment each other? Reading is great, but it's just that, reading. You CANNOT get a good idea of what the show terms mean until someone physically shows you these attributes on a chinchilla. It's just not possible to understand good vs. bad density through a book or article and you sure as heck will have a hard time understanding clarity and blue.
The advice we give to ALL new breeders is to attend a show first and foremost. This is not a huge, horrible, painful thing we ask people starting out to do. A show really helps you understand quality and often times helps new breeders choose a direction for their breeding program. Location is no excuse not to attend a show...I'm a poor college student and I have driven over 20hrs to get to a show and I've been going to shows since I was 15. Where there is a will, there is a way. Next, you should buy your animals from a quality breeder. By quality breeder we mean someone that actually breeds for quality and attends shows regularly. It doesn't have to be someone that is a member of this board, but it should be someone we have at least heard of since the chinchilla community is not that large these days and we know the quality breeders.