This is a very important question that doesn't yet have a definitive answer. Many specialists recommend starting with the spaces between the teeth – i.e. with dental floss. That way, more fluoride from the toothpaste stays in the spaces between the teeth, making them more resistant to decay.
In that case, the right order for cleaning your teeth is:
1. Rinse with a water flosser – to remove larger bits of food;
2. Clean with floss;
3. Brush your teeth with a toothbrush:
3.1 Clean the outer surfaces of the teeth;
3.2 Clean the inner surfaces;
3.3 Clean the biting surfaces;
3.4 Clean with an interdental brush if you wear braces;
4. Brush your tongue with a dedicated tongue brush – this reduces the bacteria in your mouth and gets rid of bad breath.
This answer is for general information. Your own case needs an examination by an orthodontist.