In agreement with Dattack. Basically get a 15-20G long, build a few rock caves. Use a sponge filter so fry won't get sucked up it. Put in 4or5 convicts, wait till you get a pair. Then take the rest back to the LPS and wait. Usually in a few weeks they will spawn and raise lots of little 'victs for ya. You just have to feed them some live brine shrimp a few times a day and keep their water in good quality. Move them out of the parent tank when they are about this long -----, a 20G long tank will do good to get them up to a saleable size. Thats all there is to convicts.
Angelfish IMO are the next easiest cichlid to breed. There is no 100% sure way to sex them untill you see the breeding tubes. The females will be short and more rounded, the males will be longer and narrower. But occasionally the mature male will develop a distinguishable "hump" on his forehead, the female will not have this.
Corydoras cats are easy to particurly the C.aeneus. Put 6 in a 10G, I use a sponge filter again so not to suck fry up it. Provide dense cover some java moss is great!. Build the cories a cave or two, I use sand for the substrate. Since most cories sold in LPS are juvies it could take several months before they are mature enough to spawn. Feed them well on frozen bloodworms, sinking tablets, and other sorts of foods. Keep their temp a around 76*F. Do massive weekly waterchanges, I do 50% weekly which drops the temp 3or4 degrees F. This will simulate the rains comeing and the big momma cory will go crazy. They will lay eggs all over the tank. Have another 10G setup with the same water conditions and basically the same design as the other, move the breeder cories to this new 10G(it should of course be cycled). The reason for the move is that the cories will occasionally eat their eggs, they don't really go after the fry IME. If you don't want several hundred cories let them remain in the tank with the eggs some will surely survive. Feed live brineshrimps(which will eventually to to the bottom where the little ones will eat them), keep feeding the other cories as you were before. The little ones will start getting in with the others to feed so adjust your quanity of foods accordingly. When they are about this ----- long and look like cories, move them to their own tank. A 20G long will do it should be setup similarly to the 10G spawning tank, and of course be cycled.