In cave systems, I usually carry a few ladders (min. 16), signs (up to 3 minimum), and at least a full cell (64) of torches, just in case.
Picks and shovels are, of course, default. I also default to making stone ones for speed and durability (but especially price in how common the materials are, and how quickly I can renew the supply of them), or all wood ones for quick dispatch. I won't waste more valuable materials unless I'm going to marathon it, or I hit it rich with the material. Also reason for wood/stone tools.
The ladders are in there in case there are hard to climb pits (also helps to carry some dirt or cloth just in case as well), I would need a few signs to make landmarks or in case the caves lead elsewhere, I can mark it's function, or plop some notes (one for legend, another for placement of ores, and one more as a makeshift map in case the cave is more complex than expected. Maybe a 4th or 5th one to add story/atmosphere.
Now for torches. Whether I'm making mines or exploring caves, I place torches on ceilings or walls in a way that implies where the way to an exit is. If more than one, then another sign may be needed. I would need a full cell in case caves get rather long or complex, and I need plenty of lighting. Should also help to carry some logs and a workshop and maybe a chest just in case as well. (logs are far easier to carry than cells of sticks and wood blocks. It shouldn't hurt to carry/find some coal on your way either. Those portable workshops and logs have saved me a trip quite a few times, and carrying chests cuts material transfer times considerably if especially rich by just acting as a mid-point. Farm the ores, place in chest, finish off and haul home, head back to the chest and head home. Especially helpful if you have a good distance from work site and collection point, and of course your storehouse (best-case: equidistant). It should reduce project construction times by a reasonable amount at a cheap price (time and material-wise).
I think I also tend to use ceiling lamps to work as a form of guidance with where the torch is visible acts as an arrow which direction to head towards the exit/entry point.