I've been shooting foxes for over seventy years now, at one time for a living when skins were worth decent money. I've used everything from prehistoric gear right up to the latest thermal equipment.
We had to learn the hard way making many mistakes along the way. Looking back over the years I don't think there is a right or wrong way to go about fox control. Much will depend on the sort of land you are shooting over, both farming-wise and what sort of terrain there is. Also, how much patience do you have? Fieldcraft has been replaced largely by technology and without a doubt fox behaviour has changed since the days when I started. Apart from really isolated areas foxes are far more tolerant of humans and their vehicles today which makes shooting the majority of them relatively easy to deal with.
My best advice for what it's worth would be to have a chat with a really experienced and successful fox shooter but learn from your own mistakes and experience. That should be part of the whole process. Also, learn and study fox behaviour, too many I suspect just kill foxes and in reality know little or nothing about what is a challenging and intelligent creature. Surely they deserve more?
Things are far easier dealing with foxes today than they were all those years ago but I still get the same buzz when I set off to deal with a particular animal that's been causing problems.