There are lots of great resources to assist you in studying Psalms, but here are three of my favourites:
1. Memorising some Psalms. Getting them into your head allows you to chew them over.
2. You really can't beat John Collins introduction and notes in the ESV Study Bible. They are tops. Looking up some psalms I've been memorising showed the value of this great resource again, today.
3. Geoffrey Grogan's Two Horizons Commentary on Psalms is also very useful and answers questions that some other commentaries don't.