This psalm seems to be about temptation or praying to God that our hearts would not be drawn to sin. I think that this psalm points out why we need to saturated by God’s word and why we also need to fellowship with other Christians – to help prevent us from giving in to sin. When it comes down to it, we have to keep our eyes on God and seek refuge in him and him alone.
I also liked verse 5 and praying that a righteous person would bless us by rebuking us. However, without the right heart, both rebuking and being rebuked can be difficult because its put us in a vulnerable position. I think that humility has to go hand-in-hand with rebuking.