There are two major ceremonies that must be performed in the house to clear the negetive vibes and enhance the positive flow.
Vastu puja for vastu devata is performed outside the house before the actual entry into the new house. A copper pot is filled with pure water, nava dhaanya (nine kinds of grains) and one rupee coin. A coconut is then placed on the top of the water pot. Coconut is covered with the red cloth and tied with the red thread called moli. After this the pandit performs the puja, add the husband and wife take this copper pot in the house together and place it near the havan (ceremonial fire).
Vastu shanti or Graha shanti puja, involves the havan. A havan is performed to prevent harmful influences of the planets, remove negative vibrations and create a peaceful environment. Once all the pujas are concluded, a feast is offered to the priest. He is also given some dakshina or fees for his services and good wishes.These two pujas are essential. Other pujas like the Ganpathi puja, the Satyanarayan puja ot the Lakshmi puja are optional, and can be performed if priest recommends them.