What are the effects of the character imprinted on the soul by Baptism? The effects of the character imprinted on the soul by Baptism are that we become members of the Church, subject to its laws, and capable of receiving other sacraments.
Who can administer Baptism? The priest is the usual minister of Baptism, but if there is danger that someone will die without Baptism, anyone else may and should baptize.
How would you give Baptism? I would give Baptism by pouring ordinary water on the forehead of the person to be baptized, saying while pouring it: "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost."
Further reading: CCC 1256
Note: The Ordinary Minister of Baptism is Bishop, Priest, Deacon.