How does one make sure that water comes on the whole hand completely for netilas yadayim
The first things to do to make sure the whole hand gets washed is to wash with a lot of water, and pour it slowly. It is helpful if you will separate your fingers and point them upwards as you are pouring and twist your wrist as you are pouring the water. It is noteworthy, that there is absolutely no point in pouring the water past your wrist. Some people get nervous when doing netilas yodayim, and end up pouring water past the wrist, and there is no point in doing this.
See Siddur Hagraz Seder Netilas Yodayim -1.