1 Oh, the joys of those who do not follow the advice of the wicked...To start, let's approach this from the standpoint of the one writing, not the reader. Let's accept that we cannot fully know with total richness because we are not living at the writer's time nor having the writer's experience...

 1 Oh, the joys of those who do not

follow the advice of the wicked,

or stand around with sinners,

or join in with mockers.

To start, let's approach this from the standpoint of the one writing, not the reader. Let's accept that we cannot fully know with total richness because we are not living at the writer's time nor having the writer's experience. We have not done the extensive research to understand context better. We are treating the statements for what they are: statements made. We will be looking at the statements and offering commentary. Not offering commentary as an authority, but as a practice to go through the Psalms, one of the most expressive books in the Bible, and think about what is stated, draw inspiration from what is stated, from what comes to mind. Again, we are not an authority. We are not priest, pastors, scholars. We are creative thinkers, artists, and students. We are (again) doing this as a practice to share publicly with whomever is interested.

So...the writer states here that the one who does not hang out with people who have hearts who are not on God but instead on sin (or not being spiritual, not having a heart for the spirit of God through God's means--God's word--living Word)--that person who is not hanging with such people will have joy. Their spirit will not be dampened. They will not be influenced by such people. The people are not flawed or evil. They are just people whose harts are ruled by things other than God. They are seeking peace and security in things other than God. The one who is not hanging around such people will not be influenced by them. 

2But they delight in the law of the Lord,

meditating on it day and night.

The person instead practices what we are attempting to practice publicly here: that person enjoys what the spirit has inspired (the law, the word, Jesus, the scripture, the prophets, etc.)--constantly meditating on it, reflecting on it, thinking on  it. This has psychological benefit. constantly keeping the mind centered on a subject which often centers around deliverance, hope, love, care, salvation for you now not just after death, hope for after death, those things--those are good things to think on. They can inspired a lighter spirit. 

3They are like trees planted along the riverbank,

bearing fruit each season.

Their leaves never wither,

and they prosper in all they do.

Rooted. Strong. They shall be well-nourished in their souls/spirits/hearts etc. 

4But not the wicked!

They are like worthless chaff, scattered by the wind.

The wicked will not. They will have a form of the spiritual prosperity, but it will not be the kind that comes from inviting God into our  hearts and minds.

5They will be condemned at the time of judgment.

Sinners will have no place among the godly.

The day of judgement feels like a day of ultimate judgement. It does not mean that we should not strive for justice and righteousness here. But the day of judgement should serve as a relief for those who are abused, mistreated, lied to, scorned, mocked, hated, misunderstood, and eschewed from others because of their heart for God. Those who love sin cannot and will not stand to be around those who do not share their heart. They will tolerate for a while, but will ultimately be separate from the godly. 

6For the Lord watches over the path of the godly,

but the path of the wicked leads to destruction.

And this doesn't mean that seemingly good things will not happen to the wicked, or bad things to the "good" among us. But ultimately, wickedness will be separated from God, for God wants nothing to do with wickedness and behavior not rooted in truth, godliness, and love.