The blessing should always start by the recitation of an excerpt of scripture, appropriate to the occasion. There are many excerpts which can be recited on the Holy occasion and if you are confused, you can consult the local church priest or online resources like Catholic Culture and The Parish Community of St. Joseph website. The prayers should be for the whole and the people who live in it. Remember, the Father, the Son and the Holy Spirit, ask for forgiveness, repent over your sins, and vow to lead a pious life in future.
The blessing starts with the main entrance of the house. Sprinkle the holy water at the frame of the main doorway, and offer prayers for anyone who enters or leaves through that door. After the main door, you can move to living room and spread the blessings.
Next move on to the dining room of your house; sprinkle the holy water on the frame of this room and offer prayers concentrating on the future meals which will be consumed over there. Bless the Kitchen after that, asking God to keep it saturated with food and water for the year to come, and provide everyone who eats there with health and prosperity.
Now move on the bathrooms and pray for the good health of its occupants. After that, bless the bedrooms by sprinkling the holy water.
Once you are done with all the room, offer another prayer for the whole house and beseech the Lord to bless you and your family with all the wealth and joy of the life, while keeping your on the righteous path. Dedicate your thoughts for those who are impoverished and try to help out the needy after the prayers.