One idea I am trying out in my latest survival game is to build a covered staircase at the top of an open ravine. The staircase brings you to the bottom of the ravine. Somewhere else at the bottom of the ravine I dig a semi-circular cave into the sidewall that leads to the mineshaft proper. Starting my usual 9x9 mineshaft at the bottom of the ravine saves me some pickaxes.
Then I decided to do a treasury much as this list suggests. However, my treasury is at the bottom of the same ravine with a facade carved out of the ravine's side in the style of the city of Petra. I am still working on this. I plan to store my ores in blocks stacked in an expansive, expandable underground room that just goes on and on...
Well... I think this is a no brainer, but how about spending a good amought of time looking around your area of build and plan ahead places to build roads, tunnels, bridges, that sort of "support builds" that make your life so much easier when you want to get around
Also try to make them look good instead of just putting cobblestone on the ground xD