First, when choosing female guppies, get the biggest and oldest one, these will give you more fry (babies). Then get a 1 Gallon Tank with an airstone, put some gravel in there, some plants,make it cozy. Then when she is square (really fat and bloated), fill your 1 gallon tank with water from your original tank (dont worry this will act as a water change for the original tank, just add some water to the original tank). Now put the female guppy in the 1 gallon (again this is once she is square and acting funny, if you do it too early it will stress her out) and then overnight she will most probably have the babies, and in the morning you take her out and put her back in the original tank, make sure to acllimate her back into the original tank because by this time the temperature will have changed between the 1 gallon and the original. And there you go. The Female Guppy might still be fat, but thats just because she is already working on the next batch. You cant put the fry in the tank with their mom yet, because they will be eaten :(
Some Quick Facts:
-The Pregnancy can last 4-6 Weeks
-You feed the Guppy Fry Crushed Flake Food
-You start to see color in 2-3 Months
-They are fully Grown by 6 Months, by this time, you can finally put the fry back in the adult or original tank.
I have to give credit to the people that helped me and answered my threads because I was New at this too, i followed every thing i listed here and got 18 or 19 (not sure, cant count them all to well because they move) healthy babies.
P.S. They are the cutest things