Each planet rules a specific day of the week. It is not absolutely necessary to follow this. This is for the optimum results.
The Sun's Day
Rules success, ambition, career, sport, healing
The Moon's Day
Rules psychic powers, clairvoyance, home, childbirth, feminine qualities
Tiw's Day
Rules courage, men, sexual energy, war
Woden's Day
Rules communication, education, travel, mental agility, writing, acting
Thor's Day
Rules expansion, wealth, political power, law, business, insurance matters
Freya's Day
Rules love, beauty, music, the arts, the environment
Saturn's Day
Rules karma, property, inheritance, agriculture