The psalmist appealed to the righteous to praise God because it is proper to do so in view of who He is and what He has done. Furthermore, we should praise Him in a manner suitable to His greatness, with beautiful musical accompaniment. Moreover, our praise should be fresh and skillful, not hackneyed and sloppy. God is worthy of the best in expressions of praise as well as in all we do for Him. [source][source][source]
"The "new song" is new in the sense that it celebrates a new act of God"s redemption ( Psalm 33:3; cf. Psalm 40:3; Psalm 96:1; Psalm 98:1; Psalm 144:9; Psalm 149:1; Isaiah 42:10; Revelation 5:9; Revelation 14:3)." [1][source]
" Psalm 33is a new song ( Psalm 33:3) that sings about a new world. It is the world about which Israel always sings, the new world that Yahweh is now creating. It is a world ordered by God"s justice over which God presides with faithfulness. To such a world the only appropriate response is confident and sure praise to the one who makes that world available to us." [2][source]