I usually clean my soldering iron's tip before turning it off. Yesterday I read an article where someone suggested to tin the tip before turning off the iron. Is this a good idea? And how would it help? My station is a Weller WSM-1 if it makes any difference.
An experienced colleague told me that having some solder on the tip protects it from oxidation. Following his advice, I have found that my tips tend to last longer than they used to.
I would guess that the solder protects the tip by keeping it from being exposed to the air.
Yes, tin your tip when turning off the iron.
Actually I usually turn the iron off first, then tin the tip with the residual heat. The iron will still be hot enough to melt solder for a while. You don't need extra heat to tin the tip, just enough to melt some solder. The lower temperature reduces the oxidation of the solder so that the thin coating of soler you are putting on your tip is more useful. That will also make the tip more usable when you turn it on again. A thin layer of solder on the tip helps because of its wetting action, but oxidized solder does the opposite, and leaves the tip itself exposed to oxidation.