I don't work with new hires initially but what will help you succeed in the sim is good situational awareness and IFR skills. You need to study the profiles and call-outs and emergency situations so you can fly the sim well. Lots of chair flying. When I trained, my sim partner and I taped our posters to the hotel wall and went over profiles, call outs etc pretty much every day and studied memory items, limitations and systems. If we have to teach you about pitch-power and airspeed, scan and how to figure out where you are on an approach, you will struggle.

It's about knowing what to study and when. Find a good study partner or group and work hard and you will do fine.