Summary: Praise is making much of what God has done, and isn’t always done with the heart. But worship is about who God is, and cannot be done without the heart.
This is a key passage to understand the power of praise.
Praise is an act of faith.
By praising God, the Levites were asserting their belief that God was going to do what He said He would.
Keep in mind, “praise is about what God has done.” God said He would do something, so as far as the Levites were concerned, God had already done it! It was a done deal. So they praised Him for it!
When he had consulted with the people, he appointed those who sang to the LORD and those who praised Him in holy attire, as they went out before the army and said, "Give thanks to the LORD, for His loving kindness is everlasting." When they began singing and praising, the LORD set ambushes against the sons of Ammon, Moab and Mount Seir, who had come against Judah; so they were routed.
Another translation says, “the moment they began their shouts and praises the Lord set an ambush against (their enemies)”.
Maybe right now God is saying the same thing to you. “Do not be afraid or dismayed, the battle is mine!”
Are you willing to let God work on your behalf? That is called faith. And it is activated by praising God.
God is worthy of our praises
Martin Luther said, “A person cannot praise god unless he understands that there is nothing in himself worthy of praise but that all that is worthy of praise is of God and from God.”
Praise lifts the heaviness.
Would you like to break the bond of depression? Begin with praising God!
We were created to praise Him.
1 Peter 2:9 (quickview)  “But you are a chosen people, a royal priesthood, a holy nation, a people belonging to God, that you may declare the praises of him who called you out of darkness into his wonderful light.”
AW Tozer, “The purpose of God in sending his son to die and live and be at the right hand of God the Father was that he might restore to us the missing jewel, the jewel of worship; that we might come back and learn to do again that which we were created to do in the first place – worship the Lord in the beauty of holiness.
Praise prepares us for worship.
The Scriptures present praise as something different than worship, and Psalm 95 (quickview)  is a good example of this distinction. In the opening verses, the psalmist invites praise: "O come, let us sing unto the Lord: let us make a joyful noise to the rock of our salvation. Let us come before his presence with thanksgiving, and make a joyful noise unto him with psalms" (vv. 1-2). Only then, after praise has been offered, does the psalmist invite worship: "O come, let us worship and bow down: let us kneel before the Lord our Maker" (v. 6). Commentators agree that "the order is praise first, worship second".
God teaches us to praise before we enter into the fullness of worship, for once we have learned what it means to praise the Lord with all that is within us, it is then a fairly easy progression to become an extravagant worshiper.