First off your there are four different engine failures you will have for the check ride.
1.On the roll 50% vmc
2. Minimum 500 ft AGL (simulated)
3. PTS minimum 3000ft AGL but most school have higher alt. (Full feathering and restarting)
4 Single engine approach (instrument/visual) (simulated)
Tips:
Prep your students on the ground. Be specific on what you are going to do and what the student is going to do.
Very early on get in a habit of failing both engines. Instructors that don't tend to have students that hit the wrong rudder. Ill even catch myself focusing on cutting the left one too much.
I could give you more tips but most people already covered those topics. Good luck.