Tanglos, preventing filament tangles

I've had a couple of cases where I got tangles (knots) in my filament. This is really bad because you might not discover it for many hours of printing, but eventually it'll catch up to you and ruin your print.

Tangles are guaranteed not to happen as long as the end of your filament is secure and you don't let go of it. Unfortunately, sometimes the end of the filament breaks, as happened to me, and then when you try to reconnect it to the printer, you can't be sure whether it's gotten tangled