Any tips for finding clay while we're at it? I mean, I don't want to scar parts of my land too bad, but I still want a decent yield.
Also while I'm asking, what do you think is a good amount of tracks to make to start with; or at least, what's a good amount of iron to have before considering making use of mine carts? I have at least 125 ingots of steel in my inventory, and if I plan on expanding into the Great Plains, I might as well setup a quicker route via cart.
Greater Mines are nice and all, but I dunno about working on them for now anymore. I'm split after discovering, and cleaning out, the Spelunker Mines.
Generally, clay is exposed to the surface and bordering, if not in water. I find the best way to locate it is just to explore around; this will however increase your file size and make future stuff less interesting (new stuff like swamps from future updates can't gen in already genned areas). Or if you, like I, are not to concerned with cheating, Cartographer. With cartographer, you can single out a single material to render locations of, which is really handy. First gen a normal map w/o any other special parameters, followed by a 'only 82' map for clay. Copy and paste overlay the clay map onto the other map and viola! You now have all the locations of clay on your map in one handy place.
It depends; I personally abandoned use of tracks for most uses, but if you can maintain a downhill slope the entire way, they can be quite nice. Powered minecarts are slower than walking, so don't count on those for transport.
Great mines are generally good for stone or depending how deep they are, redstone. If you want iron, coal, or diamonds, cave exploration is much quicker, albiet more dangerous. Then again, if you really don't care for cheating, you could theoretically do an overlay like for clay and dig verticle shafts (HIGHLY DANGEROUS, I ended up in a hole full of nasties of every variety when diamond hunting this way) into your satellite pinpointed mineral locations.