Ages in advance: Get no less then 6 fish of the same species at the same time, the younger the fish the better as the more control you have over it's life and what goes into the fish.
Day 1: Select your fish. Females will be around 2 or so inches for most species and very round from the toplike this: <O>< - Males will be a little smaller and shaped like this: <=>< DO NOT ATTEMPT to breed any fish that are not fully grown, sometimes you will be lucky, but most of the time you are waisting your time.
Day 2 - 13: Feed fish on live foods, frozen foods, finely chopped worms, tubiflex cubes and so on in small amounts as many times a day as you can manage. DO NOT OVER FEED! Watch them eat, and when they are done remove the left overs, you want a big filter to cope with the extra fish poo and change 20% of the water on day 4, 7, and 10 I use a syphon to get the water out AND in, so I disterbe the fish as little as possible.
Day 14: If they haven't started spawning now, feed a big meal of tubiflex cubes or chopped worm in the morning and change 25% of the water with colder water in the after noon. If they do not start spawing by day 16, start over with the feeding and change with colder water every 5 days until they spawn.
(I'll carry on assuming they spawned and laid eggs)
Day 14: In the evening they should be finished spawning. Leave the eggs sit for two hours to harden, but keep an eye on the parents or remove them as they sometimes eat the eggs. If you remove them you can leave the eggs, though its harder to raise the fry in a big tank. I recommend removing them and placeing them in an old but well washed butter tub or something like that, put a few drops of methylene blue in just enough to tint the water blue, and an air stone on very low as to keep water moving but not bounce the eggs around. Float the tub in a covered tank so that the water in the tank keeps the eggs warm, and the warm air is trapped in to keep the top bit of water warm in the tub.
Day 15: Start slowly changing the water with tank water from the breeding tank. I use a turkey baster as you can squirt eggs back in gently if you suck any up on accident.
Day 16: all or most of the methylene blue should have been changed out by now
Day 16 -19: The eggs should hatch. Keep an eye for any that go fuzzy though, if they do try to remove them very gently, if not possible leave them and add a very very small bit of methylene blue. DO NOT FEED THE FRY.
(assuming they hatch on the 19th day:)
Day 21: your fry should now be free swimming (meaning they have absorbed their egg sack and are now swimming about) add the java moss and feed on small amounts of microworms as many times a day as possible, change water daily with water from the grow out tank.
Around day 28: The fry should be big enough to move on to a larger tub with a sponge filter and java moss. You only want an inch or so of water and I use a small layer of sand on the bottom so the bacteria has something to live in as in bare tanks the bacteria will sometimes try to attach to the fry.
When the fry start to actually look like corys (you will know what I mean when you see them, they look like 2cm mini corys and oh so cute :P) you can move them on to a bigger proper grow out tank, just be sure the filter is gentle and there is no way they can get sucked it, because at this point they are still bad swimmers lol