Well it's completely down to you really. I'm assuming you mean "what race?" as in one of your threads you made you stated that you were going to become a Black Mage.

Choosing the right race can give you an edge, for example choosing Taru-Taru when becoming a Black Mage is a pretty good idea since Taru-Taru have magic and MP stats like no other. But if you sink your teeth well into Black Mage and decide it's not for you and you decide you now want Warrior you're tied to a magic based character (Not to say that Tarus don't make good Warriors, but choosing Taru won't take full advantage of the strength a Warrior could have). My point being that looking up the advantages and disadvantages of each Race before choosing a job might be wise, but again it's completely up to you, don't feel obliged to choose a magic race just because you decide to become a Black Mage.

Well hope this helps, and good luck in Vana'Diel.