To feed or not to feed is purely your choice for the grey squirrel I guess it comes down to whether you like the critters or not.
However although we feed the little blighters all year round even if we didn't we would give in when snow is on the ground as scavenging for food is so much harder then.
If you feed garden birds you may be sick and tired of squirrels destroying your bird feeders.
We too went through this stage and despite all the hype many types of squirrel-proof bird feeders are not up to the job.
The squirrel is a remarkably intelligent, powerful, animal (it's had millions of years of practice) it is not going to give in easy if it sees food just hanging around.
The only reliable solution we found was to give our furry friends their own custom feeding boxes. These are now readily available over the internet and this is far easier than seeking out a local pet store as not all stock them.
You can see how the squirrel feeder works from my pictures. The squirrel learns to lift the lid and remove the nuts from behind either a metal mesh or in some cases a perspex window. When you first place your squirrel feeder it is best to put the nuts in and then to prop it open with a pebble which will fall to the ground on first use. This method seems to educate squirrel #1 how the thing works and surprisingly the message seems to then get passed round the squirrel community as to how to work it.
We currently have 2 feeders and over 4 years all I have had to replace is the fine mesh grill once. This was only because one squirrel arrived and clearly nobody in grey squirrel land was speaking to him because he didn't get told how to lift the hatch so he just chewed his way in.
He's more than likely the same grey squirrel I saw regularly standing on the lid whilst stupidly trying to lift it by bending over. I wish I had videoed this as it was actually very funny viewing.
Make your choice carefully when deciding whether you are going to feed squirrels regularly or not. Whether you like it or not quality peanuts are not cheap and you will have to restock regularly.
Many people prefer to order their peanuts or custom squirrel food over the internet now as it normally works out cheaper as you can buy in bulk.
As to where to mount your squirrel feeder my advice would be as high as possible but so you can still reach to fill it. Also put it as far away from your house as possible.
The reasons for this are pretty obvious. Squirrels love to eat their nuts either sitting on the feeder's ledge or very close to the feeder so they can come back as quick as possible. With this regular feeding bits and pieces of squirrel food gather on the ground. This may be attractive not only to ground feeding birds but also to mice and even the odd rat if they are in your area so just bear this in mind.
Unlike bird feeders I have not found that squirrel feeders are prone to clogging at the bottom. This is more than likely because squirrels don't tend to leave nuts in it long enough to start rotting. They will normally remove every last trace of nut!
Incidentally you may have noticed the plastic bird spikes I have screwed into the end of the squirrel feeder's "perch". I have found this to be an effective deterrent against woodpigeons and as you can see the spikes don't worry the squirrels in the slightest.