I've always left my guppies get fry in the main tank. By the time I came home from school my mom was already sitting in front of the aquarium, trying to catch each and every fry, to put it into the net.
The best way to catch these small fishies is to take a net and put the cut off end of a nylon stocking over it. That way they can't escape through the holes.
I don't like breeder nets. They easily collect algae on them and look ugly, or they stress out the mother-fish. How would you prevent your guppy from getting fries again? Don't you have any males? Even if you don't have males, females are able to produce up to three times fry after the last time of fertilization without a male being around. They can do that, because they can store the sperm. That's one of the reasons why a guppy is called the millionfish.
Previously: 2x 10gal tank, 45gal aquascaped, 70gal aquascaped
Currently: 16gal FW, 40W CF, ADA Aquasoil Amazonia II/Tahitan Moon Sand, PH 6.5, kH2, gH 4