bala:
One of my first fish in my first 10 gallon were swordtails. I had my tank running for maybe a week. They gave birth that night, and now I am hooked on breeding livebearers. I think its never too early to start learning how to breed fish, but for starters, i would go with livebearers, just because they are pretty easy along the lines of breeding and raising the fry. I'm right now on my 3rd batch of fry and am LOVING it
I do plan on going on to more difficult species to breed, but that's all if I am comfortable, so like yahoofishkeeper said, it's all in how comfortable you are.
tubbs