Maturity. Financial security. Emotional stability. Loving and respectful relationship with your spouse. Patience. Freedom from drugs and alcohol. Safe home in a safe neighborhood. Extended friends and family to help and add to the love. Oh yeah!!! A heart that's ready to give and receive love! Lots and lots of it!
all joking aside, take a parenting class. learn what to expect and some coping skills, patience, sacrifice, financial planning, gather a good group of people that you trust for advice when you are tired and stressed.
There's not a whole lot to add to heart's answer... but the thing you need most... is the WANT to have a child. So many people have kids that they don't want, leaving that child unloved and unwanted, usually becoming a bane upon society b/c they never received the love they deserve. So the best preparation is to simply make sure that you want a child.
Financial training/workshops, parenting/child psychology classes, early childhood education classes, strong relationship/friendship with spouse, volunteer hours in your local public school system, safe environment, ability to offer medical, educational, and financial security, willingness to give everything up everything in the best interest of the child (including the love/appreciation from the child)... ability to step back and watch them take natural consequences for their actions, utter and total reliance on God
First off... It's probably better for the child and you... If you mate with someone healthy and strong... Then when the cub is out of the female feed it well so it will be strong... Then educate it to survive... And one day it shall leave and create it's own pack...