This could just be one of those things that everybody does, but it's so good that it deserves to be blogged about. It literally makes me smile at my own cleverness every time I bake. Using this technique will let you perfectly measure out your baking powder, without having to reach for (and dirty) an extra tool.
If you are not already doing this, you'll have to wait until you buy a new container of baking powder*. When you go to start the new one, take the lid off and then, using a sharp knife cut the safety paper that covers the top just like this: straight across the middle, and then around one half of the circle only, following the edge of the opening.
When you go to measure your baking powder, you just have to scrape the spoon against the straight edge of the paper to level off the powder. The novelty will never wear off. Trust me.
*To test your baking powder for freshness, add a teaspoonful to a small cup of warm water. If it fizzes, it's fresh; if it does nothing, it's time to buy new!