"Nevertheless, I did look unto my God, and I did praise him all the day long; and I did not murmur against the Lord because of mine afflictions."
I think that one of the best ways to praise God (which is definitely a form of expressing gratitude) is through music. Praise God From Whom All Blessings Flow is a great one to start with.
Praise God from whom all blessings flow;
Praise him, all creatures here below;
Praise him above, ye heav'nly host;
Praise Father, Son and Holy Ghost.
At one point it was one of our son's favorite hymns (probably because it's the shortest in the hymnbook), and having a family that also loves music is just another blessing in my life.