Simple question how hard is it to get tetras to breed in a community aquarium??

I have 9 ember's and 9 neons and i would love for them to spawn every now and then and get a few fry raised to increase their numbers..

when i first set my tank up last June within a few weeks i found a little baby ember tetra swimming about so they did successfully spawn and hatch at least an egg..

I know they prob do spawn but would these little fish eat their own eggs before they get to the hatching stage??

Or are their certain conditions that they favour in order to encourage spawning?? certain time of year?

Im not really interested in setting up a smaller tank for eggs etc to be fertilized, just interested to know if theres anything can be done while in the main tank that can encourage them.