Early Maiolica:

• Manganese -- Used  for outlines and fill.  Manganese looks sometimes purple and sometimes a brownish-black.
• Copper Green -- Used for fill.

Starting in 15th Century:

• Blackish impasto blue -- Used mainly for leaves.  This glaze is seen on pharmacy jars.  It looks lumpy.
• Blue from cobalt  
• Yellow from antimony
• Orange from iron rust

Late 15th century:

• Tawny brown
• Variations in greens by mixing yellow, brown or orange with early copper green or cobalt blue by either washes on top of each other or actual mixed compounds

16th Century:

• Black from a mixture of several oxides
• Deep crimson in several workshops.  Red is not a common glaze color in historic maiolica. 
• White for white on white work and high lights
• A lighter ultramarine blue from about 1550
• Aqua from copper

Outlining was primarily with blue until middle of 16th century when manganese was used.

Lusters:

Color was dependent on the combination of silver and copper oxides.

• Silver for a pale brassy yellow
• Copper for a ruby red

Luster was a difficult technique and only done by a few Italian workshops.  This technique was common in Hispano-Moresque ware.  The term "maiolica" was originally used in Italy only to describe lusterware.  In the 16th century the term became the word for all tin-glazed earthenware.