How do you choose a perfume for your wife?

I would suggest that you raid her current fragrances and note the brands and scents. If they are more floral, then choose a floral perfume; however, if they are strongly scented, then choose a strong-smelling perfume. I wouldn't say buy her the perfume that is getting low, as your wife may want a new perfume, but what ever designer make that one is (for example, Chanel or Dior), choose a perfume from that range.