Same tip applies for this trick as does for all horizontal tricks: keep the yoyo eye-level as you perform it. It helps to maintain the angle of the yoyo.
As you're learning to do the trick horizontally at first, you may want to try only swinging the yoyo with your throwhand above your freehand, and then dropping out and binding, instead of right away trying to learn to swing the yoyo while switching the positions of your hands midway through. However, learning it that way presents its own problems too (namely, your finger gets so tangled---and doesn't get untangled---that it's difficult to pull your finger out of the triangle), so you can really start out learning whichever way you like. Just make sure to get the full trick down eventually, it's a really fun and crowd-pleasing one.