I didn't have any advice when I first started, so I just did it, it seemed to work.
I hold my hand palm side up and slide it under the chicken, one leg between by ring finger & pinky finger, and the other thigh/leg between my index finger & thumb (index & middle finger for chicks)... leaving my index finger as the main support under their bodies. I "pinch" their legs between those fingers, close my hand to bring their legs in a little closer & provide a bigger platform for their underneath and slowly lift.. they don't fight or flap, it was a great first attempt. They are now several months old and still have no problem being lifted up this way..
If I don't have their thighs securely in my grip they will flap. You can tell immediately when you start to lift the weight, so I set their feet back on the ground, reposition and try again
btw.. this works particularly well for me because I can pick up two chickens at a time, just swoop them up... what a time saver when moving them here or there