The switch 3 is basically a wake 360 back except that you change the direction of rotation after 180 degrees.
Make a hard cut toward the wake with a palms down grip. When you reach the trough, spin around 180 degrees. Rotate to the left if you're cutting to the right and rotate to the right if you're cutting to the left. Tuck the handle into your hip. Ride up the wake while resisting it to get a good pop. Once you are in the air and not sooner, spin back to the front. As you come around, keep the handle low and let your arms extend out. Once you reach the forward position, pull the handle to your waist again and spin backward in the opposite direction. Land backwards and use your second pop to spin back to the front. It's very important to keep the handle at your waist and your head up when landing.
I'm coming off of the wake crooked and/or off balance.
You may be spinning too soon or your arms are out.
I can't spin back around after the first 180.
You may not be letting your arms out enough after the first 180. The line should tighten as you spin to the front as long as you don't spin too soon. Pulling against the tight rope will help you get around. If your arms are already in, you won't be able to pull against the rope.
The next step: Try the switch 5.