Well, the basic answer is that it takes patience. If you have the right combination of pokemon, then you can get the right kind of egg, but to get a female (depending on the species) might take some time. The percentage might be low, and you will have to wait, and hatch a bunch of eggs before you get a female. You can't do anything special to the egg to make sure it is one gender or another.
Breed a female Houndoom with a compatible Pokemon and hatch the Egg. I got the information from Pokemon.marriland.com
Its all about luck, Riolu has a 12.5% chance of being female when you hatch it from the egg.
you run around sinnoh and it will hatch.
You have to walk around with it. It will hatch faster if you have a Pokemon with the ability Flame Body.
pure luck
You run or bike around.
no
you need to hatch a togepi in soulsilver or heartgold then trade it to pokemon diamond
run around
Yes
you walk around for ages and ages and it will eventually hatch
in Oreburgh city in the museum