Assuming its classed as defensive driving, the one thing I impressed on my DIL as a new driver was give yourself time to think and react. That means looking at almost every situation and give yourself a 'get out' or the distance / time to react.
If you're stuck to someone's boot and / or going too fast, you're simply not going to avoid an accident in those circumstances.
It occurs to me my driving is what you'd call defensive. I drive the A1M every work day and one thing I always do when approaching a lorry that even looks like it might switch lane In front of me (a regular occurence) ..is monitor my next lane. If he moves, I will know almost instantly if I'm clear to move or not. Or simply, mirrors mirrors mirrors, all the time, even when theres no apparent reason to look.