Great topic, thanks for posting this. Very necessary nowadays with the massive amount of information arriving to our brains.
Our minds need some proper rest to work properly. I have tried many techniques. The ones that change your brain's behavior (like PNL methods) take some learning process. The fastest "ready to go" technique for me is listening to audio guided meditations of any type. 10-15 min as a start is more than the brain usually gets :)