When selecting the different colored guppies, ensure you keep 1 male to 2 or 3 females. If you have 1 male to 1 female, the male guppy may harass the female. But with 2-3 females, its attention will be split, reducing the chances of harassment.
When selecting the breeding tank for guppies, ensure you get one with a heater and a tender filter. If the filter is too strong, it may suck up and kill the fries.
When setting the tank up, it is vital to provide spots where the fries can hide. Unfortunately, parent guppies sometimes eat their own offspring. But if the fries have places to take cover, most of them will survive.