Are you a Christian and want to sign a card that bestowes blessings on the person you are giving it to? Here are a few Bible verses I have found.
Numbers 6:24-26

The LORD bless thee, and keep thee:
The LORD make his face shine upon thee,
and be gracious unto thee:
The LORD lift up his countenance upon thee,
and give thee peace.
2 John 2:1-3
Grace be with you,
mercy,
and peace,
from God the Father,
and from the Lord Jesus Christ,
the Son of the Father,
in truth and love.
3 John 1:2
Beloved, I wish above all things
that thou mayest prosper and be in health,
even as thy soul prospereth