Because people tend to be inherently self-focused when we are asked to share things for which we praise God, we often default to the things that He has done in our lives and neglect who He IS in our lives. We forget that there is so much about God for which we can praise Him and God gives us reminders in His word, especially in the book of Psalms.
In Psalm 145 Psalmist (David) uses an alphabetical acrostic to declare some particularly praise-worthy attributes of God.