I was just wondering what techniques people use for cutting curved edges? I've tried a few techniques, and still haven't found any way to get them to even approach being a truly smooth curve. Any tips out there?

Scissors.

I used to use scissors but found I can do pretty well if my X-Acto blade is relatively sharp/new. Just take it slow, but keep moving. Also lift up and pivot the stock from time to time in order to get a good angle.

Scissors work great for exterior curves, but interior ones (like arches) get bent a lot if you use 'em. Or maybe not -- I'll give it another crack, maybe.

I'm currently using an exacto pivot blade knife. It works...but not spectacular.

GACK! Don't use scissors, in fact erase that word from your memory completely. The best way to cut curves is with a fresh blade and a patient, steady hand.

A slow and steady stroke using the tip of the blade is all it takes. You're not running a race so take your time around the bend. I find that I cut curves best from a particular angle. I'm right handed so I cut right sweeping curves more easily. If you have one angle that you are best at, rotate the model page (not your hand) to suit that angle.

Hmmm, I use a compass that is designed to hold an Xacto blade. I have no idea where I got it, but I have had it for twenty some odd years, look around, I am sure they are still made, too useful not to be.

The Auld Grump

*EDIT* I am lying - I got it at Loring, Short & Harmon, a now defunct artist and office supply store.

Let's see how to explain this. With curved edges, I will slice two or three lengths and cut between them. Short little curves rather than one long one. Works rather well.