There is no real "secret" to it... Like when i pop onto a double kink rail I am not thinking "oh I am on the down part now I gotta shift my weight here for the kink". Just keep sliding rails and it will become natural eventually. The only thing I do is use my knees to help absorb the kink, that's all. So if you want to think of anything just think about absorbing the down to flat kink with your knees as your knees are shock observer. If you keep your eyes ahead of you on the rail your body will naturally adjust your weight distribution to keep you locked, don't think about that part.