Unfortunately, a problem that seems to be increasing is fish damage (especially mouth damage).
Luckily there are ways which in which damage can be reduced.
Firstly, without doubt, everyone should have a good-sized unhooking mat, a large landing net (with fish-friendly mesh), forceps/disgorgers, a bucket for water to keep the fish wet and always a form of fish antiseptic - Kryston Klin-ik, Nash Medi-Carp and Thinking Angler's Carp Care Kit are all very good.
Apart from the essentials, there are more ways in which fish damage can be reduced. Ultra-thin braid should not be used for hook lengths; it can easily slice through a fish's mouth, causing it damage.
I also believe bent hooks should not be used, even well-respected anglers have had problems with them, so imagine what could happen if less-able anglers used them.
Barbed hooks may move less while you are playing the fish, but if the line breaks, then it is harder for the fish to shed the hook. Also once the fish has been landed, it is harder to remove the hook, which can lead to more mouth damage. That is why I use barbless hooks for all of my fishing.
Always play the fish carefully, don't just 'bully' the fish in, as this can lead to damage and they will have more energy on the bank - making them harder to control. Also, make sure your clutch on your reel is set well, because if the fish makes a sudden run and your clutch is too tight, it could cause a line breakage.
If you do fish in snaggy or weedy swims, make sure your tackle is 100% fish friendly and you fish for them sensibly - with fish welfare coming first. If in any doubt just don't fish the swim.
Before lifting your catch onto the wet unhooking mat, check that the fish is lying fine in the landing net and that it's fins are flush to it's body.
Also make sure your line is not pulling on the fish, I always open my bail arm off or loosen the bait runner completely when taking the fish to the unhooking mat.
When removing the hook, try to do it in one smooth push or turn and do not just pull it out or repeatedly jerk it, if it is too deep to unhook with your fingers, don't hesitate to use forceps or a disgorger.
Once the hook has been safely removed, make sure it is far away from the fish.
When photographing or weighing your fish, always hold it low and above an unhooking mat.
Finally, always take your fish back to the water in a sling or make sure it is enclosed safely in an unhooking mat, never in your hands. Make sure the fish is totally fit before it swims off, even if it takes a couple of minutes.

Pictured above: Natty with a beautiful common.

Our thanks to 15 year old Natty who lives in Brighton, East Sussex. Wise words indeed - Ed.