Drying/aging tobacco techniques

There's a lot of variables in play here with what you are asking. Drying an over humidified bulk blend is easy, take enough out for a bowl or two and spread it on some paper or a tray. Pick out any stems or whatnot and check it every 30-45 minutes. You want the leaf to bend but not break. Depending on the ambient humidity, the dry time may vary from 30 minutes to 6 hours.
An opened tin IMHO should be smoked within a month or it's contents will dry out too much. If you came do that then simply deposit the tobacco in a mason jar for indefinite storage.
I'm sure there are a plethora of opinions on all of this and the above is just mine.

I think tobacco on the moist side is supposed to age better, this is why McClellend's Va's are so wet as well as Gwaith. Personally I just get it as it is and throw it in a jar and seal it and that's it. I dry it out when I'm going to smoke it. Tobacco in a tin pretty much has an indefinite shelf life as long as it's a round tin, the square tins sometimes the seal can go. Overall with a mixture (loose tobacco) it should be spongy when you pinch it, not brittle, not soppy wet. It's something you'll get with time and experience. I'd written off alot of flakes when I started because I was smoking them too wet and it made for a really unpleasent smoke, then when I got some experience I tried them again at the proper moisture and they're a regular part of my rotation. It also comes down to preference, some people like really dry tobacco, some people like it more on the moist side, some inbetween. Personally I like it on the moist side, I find it makes for a smoother smoke and brings out the sweetness of the flavours more.

If they are Dunhill Tins I'd advise popping whatever you choose to smoke first to allow some air circulation. I typically pop a tin, fluff the tobacco and let it stand for 15 or so minute and re-close the tin. The moisture level in Dunhill tins is usually near perfect from the pop. If you live in a dry climate and don't smoke a lot, jar it. Good smoking!

Grab a handful of tobacco and squeeze it in your fist and let go. It should unmold within a few seconds. If it does not, it is too wet. Most pipe tobacco will fail this test though. This is due to all the casing, toppings and PG that is added.