My hair is moderately wavy, and it is tangled in the morning...I gently brush it untangled ("gently" being the operative word....also I start at the ends of the hair, and work my way up as it becomes untangled...never tugging or pulling. Sometimes it does snag, but I pull away from the hair and start lower, below the tangle, and work back up), then I get in the shower.
With your back to the shower head, rinse the hair while running fingers thru it...shampoo, being careful to not knot things...massage scalp, run shampoo root-->tip. I then wash my face and neck, so I can rinse the entire "upstairs" at once. Again, use my fingers to keep the hair free-flowing under the water.
Once that is done, I get conditioner and put it on, again using fingers to keep hair untangled...emphasize placement of conditioner on the ends of the hair (that's where it's needed, not so much on the roots)...and then leave it in until the end of the shower.
At the end, rinse conditioner, using fingers to (you guessed it) keep the hair from tangling, and when drying the hair, just PAT DRY, don't scrub with the towel. Leave hair slightly damp for applying serum or mousse. (Mousse really helps me with both styling, hold, and minimum tangling. The mousse itself seems to cause snags, but that's due to the nature of the product, not a tangle.)
Hope this helps. 🙂