There are two main options that work very well for treating skins. The first option is the most common in general. It consists of using a hydrophobic liquid to make a skin water resistant. The Toko product for this is called Toko ECO Skin Proof. This video not only explains how to apply it, but also exposes a very common mistake to avoid:
Especially in the spring, skins pick up dirt, sap, and other kinds of dirt that will impede the performance of your skins. To clean your skins, use Toko Skin Cleaner. This video explains how to apply it and how to do it while avoiding hurting the fibers of the skins or the glue that holds your skins on and together:
For SkiMo, a very effective way to waterproof skins is to hot wax them. Of course this needs to be done with a very low iron temperature, just enough to make the wax molten enough to sink in the skin. If the iron is too hot, the fibers of the skin can be melted or the glue will become ineffective and your ski might come apart or off your ski base. Here is a video explaining and demonstrating how to hot wax skins:
Toko also offers a Skin Treatment Kit which offers savings over buying the components individually. The kit contains ECO Skin Proof, Skin Cleaner, and Base Tex. When you add it all up including the zippered cordura bag which can be used as a wax kit, the Skin Treatment Kit should cost $51.50, but as a kit it costs just $38.50.
Most backcountry or SkiMo skiers do not seem to worry about sharpening or maintaining their edges which is because the surface that is being skied on is generally soft and carving isn’t done much. That said, should one want a quick, inexpensive ($25), and easy tool to sharpen the side edge as well as remove any case hardened edge material from having had hit rocks, the Express Tuner and Express Tuner Kit are good options. Using the Express Tuner enables the skier to sharpen an 88 or 87 degree side angle (88 is most common for this type of skiing). The Express Tuner Kit includes a diamond stone that fits inside the tool and is effective for removing case hardened metal. Here is a video showing how to use this tool: