1 Classic colour: If it is your first pair of pumps go for a classic colour like black as it will go with most of your dresses and styles.
2 Material matters: If you like suede try to buy a colour that will not dirty so readily. Also always ask the shopkeeper if they offer after purchase services like polishing or cleaning.
3 Detachable designs: Some pumps also come with detachable brooches. This can serve as an interesting option if you want to dress up or dress down your shoes.