The genetics are interesting, and really too complicated for me in the detail many get into.
Start looking at the competition and show Guppies standards for the fish. There are many more kinds of Guppies being bred that most shows have. for the most diverse view, I would so a search for champion or prize winning Guppies and look at the shapes of the bodies and fins.
Some of the best things you can do for baby fish (adults too really) is to do plenty of water changes, keep parameters in order, and feed excellent foods.
Often Hobby breeders do not pay as much attention to the tank conditions and daily care in a way a champion Guppy breeder would.
By keeping the water exceptionally clean, changes too, you can keep any hormones diluted, not over crowding allows fish room to grow.
I would start with the mom with the upgraded care, and continue through the babies growing up. Then select the ones you feel are exceptional, in color and shape/worth the extra work. Grow and breed, this means not haveing a huge mass of fish all together with breeding and mixing with any color, finnage, shape or size.
Also if you aren't already a member of a local aquarium club, consider doing so and see if there are other breeders which you might be able to observe and talk to in person and see fish which might be considered the top level group/or already Champions.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
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