Im sure there are lots of different ways of doing it but my way is like this.
This works for most tetras, dainos and barbs. (barbs just require larger tanks)
I split the males and females up into tanks about 250cube.
Feed them up on good food such as white worm, BS, flake etc.
When the females look nice and fat - after about 3- 5 days depending on age i move them into a breeding tank.
Just net stright into the breeding tank, the shock helps with the breeding.
The breeding tanks i use are 300 x 150 x 150mm wit a layer of 1.5mm mesh (mitre 10), mesh should be put in so fish can't get under.
I get water from a drum that has a pump pushing water thru a stocking of peat. Water should be nice and brown or rich tea color.
Water about 60 - 70mm high.
A small clump of moss is added.
I add the fish just about 1hr before lights out,
The next morning there should be a nice layer of eggs, if not wait another 24hrs. If still no eggs put the pair back into the original tank and feed up again.
You don't have to split the fish up you could just pull the right out of a display tank into the breeding tank.
Once the you see eggs take adults out and mesh and wait. So species do need darker conditions to hatch, bit of newspaper or poly works well.
For some species i also add a drop of meth blue.