The Bible doesn't give instructions on meditating on the Word. In fact, the words meditate and mediation don't even appear in the New Testament. But the word "meditate" means to think deeply or focus one's mind for a period of time.
Personally, I think mediating on the Word is a good idea. Believers may come up with many different ways to meditate on the Word but here are what I hope will be some helpful suggestions:
1. Take a verse or passage and read it several times
2. Pray for the Lord's illuminating work in your heart
3. Write the passage out on a piece of paper and highlight or circle what you believe to be the key words
4. Think about or look up the definitions of those key words even if you're familiar with them
5. As yourself some of the following questions:
Does this chapter/passage/verse teach or reveal anything about God Himself?
Is there an example or instruction about godliness in this passage?
Is there an example or instruction about sin that I need to take note of? (Is there a command to obey?)
Is there a promise for me to take hold of?
What can I praise and thank the Lord for based on this passage?
Is there anything the Lord is speaking personally to me from this passage?
What would the Lord have me DO or what areas of my life do I need to surrender to the Lordship of Jesus? (Commit this to prayer.)
Doing these things will help you as you meditate on God's Word.