If you would be heartbroken if you lost a chicken, then do not free range. If you free range there is a chance that you can loose them. If you can take the risk, here are some things that worked for me... kind of sort of.
Don't let them out every day at the same time. Predators love a schedule.
Don't let them out if it is very windy or heavily cloudy.
Do have a MATURE rooster, a rooster is not good at flock protection or control until a year old. But at a year old, I have had much great success from overhead flying predators, however some rosters are better than others.
If ... when you get hit by a predator, go into lock down for several days. This will give time for a hungry predator to move on.
This works for me,
Mrs K