There is no Church law about this. You are free, it is a private matter. There is no public rule or right about how to pray the Rosary. The Vatican has not published any official order. It is a tradition, and different countries have different practices. Usually, the most common practice is to start with the Creed, then the three Hail Marys. In some countries, people add intentions for faith, hope, and love for the first three, and then start with the mysteries. The Prayer of Fatima is also usually included.
It is not established by the Vatican as an official order of how to pray. In the future, it could be good if the Church published a kind of Ordo Rosarii, approved by the universal Church, but since this has not done, it depends on tradition and private devotion. Praying an extra Hail Mary after every Rosary will not harm you.
Follow-up Question: When praying three rosaries in a day, does Bishop Schneider pray the Creed and Hail Holy Queen after each rosary, or just once for all three?
When I pray three Rosaries, I usually say the Creed only at the beginning. The Rosary was originally composed of the fifteen mysteries as one prayer, and it starts with the Creed, the symbol of faith. This is sufficient, but it is up to each person. If someone wants to pray the Creed before each Rosary, it is not harmful.