You'll find all sorts of approaches. A lot of folks clearcoat with a gloss acrylic (Future, or a variety of other hobby specific acrylic gloss clears) over just about any kind of base paint job, and once it's fully dry use either oil or acrylic washes. Cured Future is VERY tough. Or clearcoat with a Lacquer product from Testors, Alclad, etc. These go over most basecoats as well, even acrylic as long the base is fully cured and you're not just dumping the lacquer on there. Then you're pretty much impervious to any kind of wash thinner except lacquer thinner. Can't imagine a lacquer thinned wash, unless you're modeling a desert wreck eaten away by time and the elements. ;-)
Oil washes get good press due to the great flow properties of heavily thinned oil paints, infinite color variety, and the slow drying time giving you plenty of time to work with it. I personally prefer the clay based washes from Promodeller. You get a huge amount of wash for your money, and the nature of the product makes aircraft panel line washes a snap since it doesn't require any sort of mixing or application skill. It's clay based so it doesn't react with anything, so application is as simple as smearing it around where you want it and wiping it up everywhere it shouldn't be. If you decide to give armor a try, though, or just want to do dot washes or filter washes then it may not work as well as more 'traditional' thinned oil or acrylic. Those techniques seem to need a variety of colors. No experience there. The Flory Promodeller stuff is mainly for making things dirty. :-)