I sometimes start over and over until I get a female, but only if I'm really bored. When I decided to restart my Diamond, I tried to get a female Piplup. It must have been at least 20-some times when my friend asked if he could get a Turtwig, which he needed to finish his Pokedex. So I restarted to get it for him, and wouldn't you know it. It was female. I traded with him until he got an egg from her, then traded back. I kept it, and I have a female Empoleon now. I also have a female Torchic on my Sapphire.