The race of your character should be reflected in your concept. Each race has its own culture and history and should have a different style of play. You should also look at the races that are common in the kingdoms and think about how you fit into the culture that you play in. The races have a common appearance and playing a non-human has a minimum costume and make-up requirement that you should take into account. In addition each race has restrictions surrounding which skills and abilities they can take. You should read the World Book for more details.