2 Tim 3:16 says all scripture is given by inspiration of God and is profitable…. For scripture to be profitable to you, there are three things you should do:

Understand the scripture – Job 32:8 – it is the Holy Spirit’s desire that you understand the words of God.  He gives them to you by inspiration [2 Tim 3:16], which is how you understand anything you’re reading in the Bible.  You cannot expect to “get it” without the Holy Spirit.  Jn 16:13, 14:26.

I have looked up many references on-line.  Two things are abundantly clear.  Most commentators don’t have a clue what they’re talking about.  And most commentators regurgitate what they learned from someone else.  They can’t help you.  

You must “get on your knees” before God and cry out to him for understanding.  He knows what he wrote better than anyone in the universe.  And if you come to him with a humble mind and a believing heart, he can help you perceive the words.  God didn’t write them so that you cannot understand them, Prov 8:8-9.

Discuss the scripture – Mal 3:16 – when you’re digging through a passage, and you’ve come up with something that makes sense, talk it over with others who spend time in the word and who are doctrinally sound.  They’ll help you by checking other cross-references and considering other doctrines.  

When perception comes from the words of God by the Holy Spirit, others who know the Bible will understand.  You won’t have to “persuade” them.  It will be clear.  

However, if you are off-track, they can help you get back on track so that you don’t end up with a doctrinal error.  And you help others with their Bible study when you discuss things with them. They take an interest in the words and dig deeper to help you, whereby they help themselves [Prov 19:8].

Apply the scripture – Prov 2:2 , see Prov 22:17; 23:12. When you perceive the words of understanding, apply them to your heart.  Live by them.  Man shall not live by bread alone but by every word that proceedeth out of the mouth of God, Matt 4:4.  Be ye doers of the word, and not hearers only, deceiving your own selves, Jas 1:22.  When the scriptures show you where you’re wrong, depart from evil, Job 28:28.

When the scriptures become a part of your life, they will change your life.  And they will help you understand other passages as you continue to study and perceive the words of God.  It does you no good to know what the Bible says if what you have learned doesn’t affect the way you live.  Knowledge puffeth up, 1 Cor 8:1.  It’s through the words of God that we grow in the grace, and in the knowledge of our Lord and Saviour Jesus Christ, 2 Pet 3:18.

Conclusion: when you understand the scripture by the Holy Spirit’s inspiration, and you discuss the Scripture with Bible believing students of the word of God, and you apply these words to your heart, the scripture is profitable to you.  It is then able to make you perfect, throughly furnished unto all good works.