Discernment is essential in making wise decisions. Paul tells the Philippians that he prays that their love grow even more in knoledge and discernment. I believe discernment is the wisdom of God. In order to make wise decisions - decisions that seek to glorify God and not ourselve - we need spiritual discernment.
I believe Paul asked God to give them discernment because he knew they would need to beable to know the difference between right and wrong. Discernment is about wanting what God wants. Paul wanted them to focus on the will of God for their lives and not on what they wanted or desired.
Selfishness clouds discernment because the focu in not on God. Self-centeredness and pride clouds our judgement. Discernment is a gift from God to be used to exalt and glorify God. That's difficult to do when we seek the will of self.
What may appear good may not always be what's best. God knows what's best. Many things and ways look good - and they may be - but if we'll allow Him - He will always do whats best. That does not always means best to us. But - it's always best for the glory and honor of Him. All things work together for "what's bets to God" - for me.