Themes and Forms of the Psalms

This video summarises the main themes and forms in the psalms in an interesting manner.

For a more academic approach
Yale Uni (literature app) http://oyc.yale.edu/religious-studies/rlst-145/lecture-21#ch3 or
Biola Uni https://www.youtube.com/watch?v=22js7Jr9vwY

One possible grouping:

These can be grouped in many different ways, by theme or poetic style. For example the Catholic Encyclopedia:

Wisdom Psalms	35, 36, 48, 72, 111, 126, 127, 132
Royal Psalms	2, 18, 20, 21, 45, 72, 101, 110, 144
Laments	Individual: 3, 21, 30, 38, 41, 56, 70, 119, 138, 141
	Corporate: 2, 44, 80, 94, 137 2, 43, 79, 93, 136
Thanksgiving	Individual: 17, 29, 31, 33, 39, 65, 91, 114, 115, 117, 137
	Corporate: 64, 66, 74, 106, 123, 135
Enthronement	23, 28, 46, 92, 94-98
Praise	8, 18, 32, 66, 99, 102, 103 , 110, 113, 116, 144-148
Acrostics	9, 24, 33, 36, 110, 111, 118, 144 An sweep of the Psalms.