Before one takes on the task of explaining Scripture to make it plain to others & how it may apply to changing our lives, one must appeal to the One who can open the eyes of our heart & mind to understand the Scriptures. Without our Lord's illumination & the Spirit's clarification, we would be lost.
We are foolish & slow of heart to believe. We are ignorant & dull of hearing. We have preconceived ideas that can also cloud our discernment. We truly need help & the Lord desires to help us.
Second, we need to immerse ourselves in the text by understanding the context in which it is found.
The passage above is PART of a larger context that starts at the beginning of John 13 & ends at the end of chapter 16.
John 13:1,2 It was now just before the Passover Feast & Jesus knew that His hour had come to leave this world and return to the Father. Having loved His own who were in the world, He loved them to the very end.
John 17:1 When Jesus had spoken THESE THINGS, He lifted up His eyes to heaven & said, “Father, the hour has come. Glorify Your Son, that Your Son may glorify You.
I would read this context repeatedly--over & over, immersing myself in the context, seeking to think as God thinks & picture myself back at that time, when John wrote about this.
When one does this, themes & patterns suddenly begin to emerge.
The next step is to make as many observations as one can, asking the reporter's questions: who, what, when, how, where, why this or that, etc. and narrowing those to the passage at hand. Questions open so many doors that you can go through & stimulates your thirst to know more & how it applies to us.
One wants to know WHAT the text actually says before any interpretation is made. This saves us from adding things into the text that are not there (presumption & speculations) and/or taking things away from the text because I wasn't thorough to properly examine it in detail.
Then as you said, we can seek to 'harmonize' this passage with the rest of the counsel of Scripture. Correlation is an important part as well, to keep us from making incorrect interpretations & conclusions.
Remember the often repeated verse throughout Scripture: 'by the mouth of 2 or 3 witnesses, let every fact be confirmed.' Let Scripture interpret Scripture.
Take note to get the setting, the cultural issues, the language used (past, present, words used that may need defining, etc.) & whether it be narrative, prophetic, personal, parable, figurative, etc.
Now by the grace of God & the spiritual wisdom from above, we can begin to see what the writer intended us to see & understand. Our hearts should burn within us & humble us when the Lord opens our minds & hearts to see as He would have us see.
One must remember, too, what the Apostle James cautioned us about.
James 3:1-12 Not many of you should become teachers, my brothers, because you know that we who teach will be judged more strictly.
2We all stumble in many ways. If anyone is never at fault in what he says, he is a perfect man, able to control his whole body.
3When we put bits into the mouths of the horses to make them obey us, we can guide the whole animal.
4Consider ships as well. Although they are so large and are driven by strong winds, they are steered by a very small rudder wherever the pilot is inclined.
5In the same way, the tongue is a small part of the body, but it boasts of great things. Consider how small a spark sets a great forest ablaze.
6The tongue also is a fire, a world of wickedness among the parts of the body. It pollutes the whole person, sets the course of his life on fire, and is itself set on fire by hell.
7All kinds of animals, birds, reptiles, and creatures of the sea are being tamed and have been tamed by man,
8but no man can tame the tongue. It is a restless evil, full of deadly poison.
9With the tongue we bless our Lord and Father, and with it we curse men, who have been made in God’s likeness.
10Out of the same mouth come blessing & cursing. My brothers, this should not be!
11Can both fresh water & bitter water flow from the same spring?
12My brothers, can a fig tree grow olives, or a grapevine bear figs? Neither can a salt spring produce fresh water.
Nehemiah 8:8,12 They read from the Book of the Law of God, distinctly communicating its meaning, so they could understand what was read...Then all the people began to eat & drink, to send out portions & to rejoice greatly, because they understood the words that had been made known to them.
Lastly, how can this passage be applied to our lives, just as it was applied to the disciples that heard it? For them Christ was leaving; for us Christ is returning.
I will leave the details & work to you. LOL. I pray if you are doing it, that the Lord will open your mind & heart to understand & for power by the Holy Spirit to speak with authority & bring people to understand & desire to obey, applying it to their lives.