Colossians 3:16 tells Christians to:
Let the word of Christ dwell in you richly, teaching and exhorting one another with all wisdom, singing psalms, hymns, and spiritual songs, all with grace in your hearts to God. (NET Bible)
This passage does not instruct us in the how of letting Christ’s word dwell in us richly. Bit it does instructs us to let His word dwell in us richly.
By whatever means then — daily scripture readings, MP3s, podcasts, devotionals, sharing with others, listening to a sermon, meditations, general revelation from science and nature — the key to the first part of this passage is to let the word of Christ dwell in you, and to let it do so richly.
This means, we should let His word seep through us into our inner-most being — into our hearts. Once there, it will purify us and clean us and change us further into His likeness.
But this is not a one-off exercise. To have the word of Christ dwell in us is to have it stay in our hearts — today, tomorrow, and forever.