Sorry to disagree with those who support this rule, but I've found this doesn't work well for me.  I was taught differently as a boy scout, and continued that teaching when I taught the same merit badge many years later.

When beaching a canoe, I try to have the bowman climb out first as I steady the canoe with a paddle on the bottom, with the shaft against the side of the canoe.  Then, after he steadies the bow after pulling the canoe further onto the beach, I either climb over the packs, or amidships when empty; or, I step out into the shallow water.  Not a graceful sight, but it has worked.

Similarly, when launching, I've found the sternman enters first, and can control the craft as well as steady it when the bowman shoves off into the shallow water before climbing in.  

Safe journeys.