I've heard great things about matrix, but I only really use signal. It's the only private messenger that's convieniant and simple to understand for non tech savy people to switch to (at least in my experience)

I think ideally you'd brush your teeth after every meal, but that would require having a toothbrush with you at all times and I'm too lazy for that. Brushing twice a day is good enough; once around 10-15 minutes after eating breakfast/ the first meal of the day and right before bed.