This thread links really helpful advice about the different ways people raise livebearers etc, really worth reading through!
Welcome to the colourful world of Livebearers - fish which give birth to live young, rather than which hatch from an egg outside the mother's body. In the hobby, there are generally 5 species of what I would class "Common" livebearer:- Guppy, Molly, Platy, Swordtail and Endler. Here is some...
www.fishforums.net
My personal advice based on breeding mollies, guppies and platies for a few years varies, depending on what you want to happen! Do you want to have them all raised in the same tank like a colony breeding set up? Rescue every fry? Adults will eat newborn fry if they have the chance, but there are different methods to try to prevent that happening. Some use breeding nets or boxes to contain the fry safely for a few weeks until they're big enough to no longer be considered a snack for adults, or some people will use a lot of live plants for the fry to hide in. That makes it easier in terms of not setting up another tank or raising them in a breeder box, and it tends to be weaker or sickly fry that get eaten by adults if done this way, so it can actually be helpful that only the stronger ones make it... natural selection, kinda.
Or some set up a nursery/grow out tank and raise the fry in there, I've done that too, but depends whether you're able or want to set up another tank! I highly advise finding out if a store is willing to take batches of livebearer fry once they're old enough to sell - most of the big chain stores won't, so you'll want to look for privately owned, local fish stores. They're more likely to take them off your hands, and some may give some store credit or something in exchange for a nice batch of healthy young fish.
Otherwise, you're looking at trying to sell them privately via places like Gumtree, which can be tricky and time consuming. I shut down my livebearer breeding entirely when my local fish store who used to take my batches of young fish closed down... I didn't have time to arrange private sales of 2-3 fish at a time when the adults were churning out 30 or so fry in each batch!
Don't get me wrong, I really enjoyed breeding them while I did! It's fun to raise adorable baby fish and watch them grow, see what colours they turn out to be, etc. It's just that the numbers can get overwhelming quickly if you're saving all the fry, and don't have a plan for where they will go once you have 30, 40, 50 young fish bursting your tank at the seams! lol
