Need advise on buying a car in Mexico city. Plz help!?

I am moving from Geneva to Mexico city next month. I am 29 years old and have just got my driving licence. I have no driving experience apart from the lessons I took. We will be living in a nice neighbourhood in Mexico city (Lomas de Chapultepec). Now I need to buy a car! What should I go for? New car or used? I am so confused. Safety is the only thing I am looking for, I have no preference in cars and no knowledge of them either.