Fold it rather than tracing it out.
The step in baking a cake that is always the one I find the most annoying is never the creaming together of butter and sugar, or the icing of things, or even letting it cool enough for me to decorate it without the frosting melted. It is, without fail, cutting a round of parchment paper to line the bottom of the pan. For some reason that task is a hurdle I have trouble getting over even though I know that the extra non-stick insurance of parchment paper is worth it, especially after taking all the time and effort to put together a cake to begin with. I know, I know, you really should be buttering the cake pan, putting parchment in it, and buttering the paper. But we all have those little tasks that we dread, and parchment paper is one of mine.
Until, that is, I learned a trick from culinary school that made things so much easier. Rather than putting the cake pan on a sheet of parchment paper and tracing around it, as I had been doing, you can simply fold the paper in a way that lets you cut a circle of the correct size without any tracing. The technique is called a cartouche, and it's used in French cooking to create a parchment paper lid for pots to regulated the temperature and moisture of the dish as it cooks. You would use one over a braise, for example, or on top of shallots you were sweating to avoid losing too much moisture from the dish. In many cartouches, you cut a hole in the middle to allow some amount of steam to escape, but of course you don't have to, and it allows you to easily make a parchment round for a cake pan.
WATCH: Parchment Paper or Wax Paper?
Basically the technique goes as follows: take a sheet of parchment that's as square as you can get it. Fold it in half. Then fold it in half again. You'll have a square with two folded edges and two open edges. Fold that diagonally to make a triangle, keeping the folded sides together. (it's a little tricky to explain, but Serious Eats has good step-by-step photo directions of the process.) Then you fold that triangle one or two more times lengthwise to make a wedge that has a pointy end and a wide end. put the sharper end in the middle of the pan you're using and make a mark where the edge of the pan lies on your wedge. Snip the paper there, unfold it, and voila: a circle.
Another hot tip: if the paper curls in on itself, as so much parchment tends to do because of being stored in a roll, you can just crumple it in a ball and unfold it. That should get rid of the curling under problem. May your days be easy and none of your cakes stick to the pan again.