You want to be on the balls of your feet, not your actual toes. Really bend your knees (sounds sooo much easier than it actually is) and if you engage the turn or traverse with your ankles and really get up on the balls of your feet, another thing you can do to keep from tiring out is rest your shins on your boots with your knees bent, ankles flexed and on the balls of your feet. This will alleviate some of the pressure on your ankles while you are still spending a lot of time on one edge. It's hard work, exhausting but totally rewarding! Keep it up, you'll get there!
Every turn is a blessing.