A tip I was once given on sawing wood is to always begin with an upward stroke towards you. Trying to make the first cut by pushing the saw downwards is much more difficult and accident prone.
Another thing about wood is that sometimes hammering a nail into wood takes an extraordinary amount of effort. This is due to "knots" in the wood. You cannot hammer nails into these knots - they are like iron. If wood is painted you cannot see where the knots are, but will know when the nail won't go in. I encountered this problem recently while installing an Ethernet cable in my house and when clipping it to the skirting board (baseboard).
