I realize this may not be the most exciting of topics, however if you have an external fixator in place, this is certainly of interest to you while you are undergoing treatment. I think we can start this conversation with the old adage in medicine "if there are a hundred ways described to do something, then none of them are great". This is particularly true for pin care.
While I was a fellow we used 50/50 saline/hydrogen peroxide. This works, however prolonged use seems to irritate the skin - especially during the winter. For patients who had problems we switched to a dilute chlorhexidine/saline solution and I feel as though in general this is better tolerated - and so this is what I have used in practice. I was taught to keep the pin sites covered in general - however there are exceptions to this. Mature pin sites (ie there is not active adjustment, lengthening, etc ongoing) where the skin has sealed well around the pin site can potentially go uncovered - or at least be uncovered around the home (I still think its a good idea to keep them covered outside. I was also taught to clean the "gunk" away from the pin/skin interface to allow for any drainage to drain, and not collect under the skin. In the beginning this is a great idea, because even healthy pin sites will drain. However, mature pin sites may seal off and I think its OK to just gentle clean them without disturbing the "scab", as long as it doesn't look like theres any fluid thats trying to drain. Again - this is really more of an art than a science.
Some other anecdotal things I have noticed with pins which I generally believe to be true (and I think most people would agree)
-Pins or wires traversing large amounts of soft tissue will always look "angrier" - ie femur versus tibia
-In general pin sites seem to calm down and mature faster than wires
-If there is swelling from surgery and the skin is getting close to the ring - a piece of cardboard (like from a tissue box) between the ring and the skin will prevent problems
-To that same issue - wrapping a wire or pin site that is near a ring with some extra wraps of gauze will actually help to push the skin away and prevent irritation
-Wires in the forefoot are always less well tolerated than those in the hind foot
And a very important, well known fact:
-A pin that was previously well tolerated/painless that suddenly becomes very painful is likely infected (remember, redness and drainage around a pin site can be very normal, but sudden increased pain is not)
And finally, there are many great videos out there on how to deal with pin care - here is a great one from Dr. Rozbruch at HSS