Be sure to separate the eggs carefully; even a small amount of yolk in the whites will prevent them from beating up properly.
Using parchment to line the tin cans will cause the bottom to sink slightly when you invert the cakes to cool. I thought it was negligible for the tin cans, especially when compared to how hard it was to get the cakes out without the liners, but it may be more noticeable for a 6-inch tin, in which case it might be better to use a tin with a removable bottom.
In the several trials I did for this cake, the leavener proved to be the hardest for me to get right. I was looking for a very close crumb and ended up with one that was still slightly more open than I was aiming for. If you don’t mind this and want a tall cake, keep it at 1/4 tsp baking powder as written. If you’d like a tighter crumb, decrease to 1/8 tsp baking powder.