How to teach kid's a routine to make sure they are brushing every part of their mouth in the most effective manner? Any videos or tips on how to do this?

Oh I love this question! This reminds me of the time my 3 year old cousin is learning to brush her teeth. Her mom would play this video non stop: https://www.youtube.com/watch?v=Pd4WnsXwdqw And when I was babysitting her, I had to play this for her whenever she brushed her teeth and the song was stuck in my head. It is really really really catchy. I still get nightmares of it every now and then hahhaa.

By doing it with you lo everyday!!! I have been doing it together with my 3 year old. And i make it fun. Ill sing a song and make silly faces whilst doing it with him. Its hard to ensure they brush every corner. For a start at least they are brushing. Many kids, dont even want to brush!

Try incorporating song while they brush and get them to act out parts of the song : for example placing toothpaste on a toothbrush and brushing for 30 seconds on one side - counting...