Number of steps don't particularly matter, outside of trying to have a multiple of 5, so that you're either at the 'finish exploring' or the boss room of the path, or at the crossroads (note there is no particular benefit to ending here, so feel free to have one step less than a multiple of ten). If you have resources to spare at the end of exploration, then invest in steps.
Personally, I prioritized stats in the shop, starting with INT and MAT to boost the early magic stone/energy economy. At certain levels of INT, elementals will give multiple basic magic stones in return for one (!) magic stone of their element, allowing for net magic stone gain even in the long run, provided we can keep up with increasing stat requirements. MAT just allows us to get more from each ore deposit, making this more convenient (the elemental stone per basic stone spent remains the same, but now we get the same out of one ore deposit as two earlier, and it also boosts energy drained if you need it).
Roughly during and after boosting stats are the crafting, NPC, or recipe upgrades, in whichever order you prefer. I recommend Fairies and tool/magic processing tables, though. The former for more choices as to what elemental stones to spend for X amount of energy, and the latter because tables allow you to craft as many times as you have materials, tools are important for getting the most out of each step, and magic processing tables can offer the option to craft capture stones. Note that both crafting and NPC options are still randomized, so the extra option isn't always helpful, but more rolls means more chances for something useful to pop up. Gold key and bomb recipes are helpful, though the latter is expensive in terms of elemental stone investment to craft in the field.