Two common issues we see in the hockey stop are:

1. The trailing skate tends to drag behind during the stop.
2. Tend to catch the outside edge of the trailing skate.

The reasons for both of these issues is that we do not have enough weight on the trailing foot. We want the weight dipersed more evely between both feet. With the weight on the balls of your feet you should be able to swivel your hips back and forth easily.

Another good exercises is standing still and pushing lateral with one of your inside edges and allow the other skate to feel the edge dig into the ice as we slide laterally.

As you get more comfortable we want to be able to swivel the hips quick and "stick" the eges into the ice for that quick stop.