When I started this business, I have spent a considerable amount of time collecting building materials, most in the form of pallet wood. Those are very easy to find and most of the local businesses are happy to spare some, especially if they are not so new (which is great) or simply damaged in some way.
Once you get to them, next step is breaking them down and the rest of the process (denailing etc). I have tried multiple ways to do this efficiently, from crowbars, to bricks, mullets and whatever else you can think of. Most of the time, it was very painstaking process taking way too much time and effort, until..
Until I have bought a tool called reciprocating saw with long blade, variable speed and 750 W power, my trouble days were over. You can find a lot videos on Youtube on how to use this tool (pallet pal for example) or that tool, but honestly for me-that saw does it.
Simply pry the boards a bit with a crowbar and cut the nails with reciprocating saw-it will fall apart and the only thing you got left to worry about are nails, most important thing is that almost no wood will break in the process. Whilst I was hammering away, jumping on pallets and muscling away with big crow bars, about 30% of wood would break and end up in the dumpster. It is a pain in the butt, because not only the wastage, but also disposal of broken boards.
So, there you have it, in my humble opinion there is no better war that cutting the nails with the saw I mentioned above and getting the nails out later.