Many Psalms have more than one message, and mean different things to different people. But the following list should at least help in suggesting which Psalms to turn to according to your mood and situation

Which Psalms to Turn To

When Studying Torah	1 19 119
In the Synagogue	5 26 27 63 65 73 84 96 122 135
In Nature	19 104 148
Desire to Repent	40 51 90
After Committing Sin	25 32 51 130
Sad, Depressed	30 42 43
Cannot Sleep	4
Lonely	25
Disruptive Changes in Your Life; disaster	46 57
Frustration at Wickedness of People	36 52 53 58
Anxiety from Enemies	3 5 6 7 9 17 22 25 31 35 38 43 54 55 56 57 59 71 140 142
Anxious Concern about Livelihood	23 62 68
Suffering, Afflicted	38 102
Want to Pray, say psalms, speak to G-d	51
Need to Increase your trust in G-d	22 23 56 62 84 123 125 128 131 146
Single hoping to find a soulmate	68
Uplifted feeling	8 19 24 47 48
Need G-d's help, protection	70 91 121 130
Confused by success of wicked, envious of rich	1 37 49 73
Beset by old age	71
Perplexed by injustice and G-d's distance	10
Doubts about faith	1 2 19 37
Feeling confused religiously	25 143
Israel, Jews, Judaism pressed abused threatened	53 74 83 124
Betrayed, hurt by others, someone close	35 41 55
Feel abandoned	27 88 142
Feeling thankfulness to G-d	9 18 65 66 116
Grateful to G-d for success, prosperity	65 144 147
Feel threatened, anxious or afraid	4 22 23 56
Slandered, abused verbally, victim of wrongdoing	39 64 120
Great troubles and distress	6 31 34 55 69 77 86 88 107 121 138 142
Feel humiliated by people	22

Source: Jewish Spiritual Practices by Y. Buxbaum pg. 366-367