Re: "Don't use strength!"
I know it sounds like a contradiction, but I think you need a bit of strength to learn the mechanical ways the techniques work. Then, as you find slightly better ways to effect the techniques over time, you will begin to use less strength. I think it is easier to learn starting from using a bit of strength than from being too light from the get go (and never go thru the process of using strength). Just my 2c.