Scott180...
Neon tetras, Paracheirodon innesi, are difficult to sex but ripe (egg-laden) females are easily recognized by their increasing girth. They are difficult, but not impossible, to breed and it is even more difficult to hatch the eggs because they are susceptible to bacteria. Spawning is difficult to detect because the eggs are non-adhesive and quickly sink to the bottom.
I had a few rare successes many years ago with Neons using a technique outlined by Dr. William T. Innes in his book Exotic Aquarium Fishes. I would prepare a tank with very soft, acid water (I used distilled water filtered through peat moss). I used a gravel bottom, boiling the gravel in water before putting it in the tank. Then I would put my breeders into the tank and feed them Daphnia (frozen would be acceptable) to get them 'in the mood'. I also kept the light level pretty low. Once I was sure they had spawned I would remove the parents and keep the tank dark for a couple of days.
When I finally noticed fry I would feed them on strained, hard-boiled egg yolk. This is prepared by straining the yolk of a hard-boiled egg through fine cloth (like cheesecloth) and placing it in a partially filled bottle of distilled water. Then boil the bottle and its contents for about 10 minutes and keep it refrigerated. To feed the fry, shake the bottle and add the mixture drop-by-drop. After a couple of weeks the fry can handle baby brine shrimp and/or finely ground flake food. (Note: the egg yolk mix will keep for about a week in the 'fridge'.)
Good luck!