Worthwhile reading for the Lord’s Day here:
A Catechism on Judgment in Worship
Free Example:
How can I judge something that I already like or dislike?
First, we should make our prejudices explicit. If we like something, or dislike something, we should own that to be true.
Second, we should ask why we like what we like or dislike what we dislike. If we do not have reasons, we ought to seek them. Understanding why we love something is part of the way to learning what it means, and learning about our own hearts.
Third, we need to compare what we currently like, or dislike, with some standard of what is good, or true, or beautiful. What I like does not become good by virtue of my liking it; rather, I must learn to love what is good. What I dislike may not necessarily be bad; rather, my sinful heart may dislike things that are true. We should not defend our preferences because they are familiar; we should learn to like something because it really is good, and then make the good familiar.
Sanctification is all about unlearning some loves, and learning new ones.
Unknowing 
Man, that was good, wasn’t it?
Yes, very good. Answering serious questions properly is always a good thing. The great thing about a catechism is that it asks the worthwhile questions.