Opening rituals are performed before the actual working to help you shut out ordinary reality and get you in the right mind-set of the working. Additionally it protects you from intrusion by undesirable entities that are usually drawn to places of heightened energy.
Before you start, get all the material you need for your ritual and place it on your altar, turn off your mobile, disable the bell and make sure you will be undisturbed throughout the working.
Stand before your altar and start gathering energy, for example by using stödhur. Once you feel you have gathered enough form this energy into a sphere at your centre. Now slowly visualise this sphere growing beyond your body into the room.
Continue moving the borders of the sphere along to the walls, floor and ceiling of your working space and seal it off completely so that nothing from the outside may penetrate unless you desire it.
Face north and seal the northern side of the energy barrier with the sign of the hammer of Thor. Continue with East, South and West.
Then face north again and visualise the hammer on the ceiling as well as on the floor.
Finally release the sphere from your energy and start with the ritual you prepared.