There are a few different techniques but I tend to pick them up by going to stroke them. This often causes the hen to flatten to the ground which is a natural instinct as if in anticipation for a cockerel to come along and mate. At this point calmly close your hands over the birds body making sure you include the shoulder like part of the wing up by the neck to prevent them from flapping. It’s important to have a relatively firm hold of the hen so that she feels secure but not too tight that you restrict her breathing or risk causing injury. Once you have hold of them you can position the hen practically under your arm.