The biggest two things about surviving sim training as a newhire at a regional:

1) Initial new-hire is not party time. Its not college all over again. Hunker down and study, save the drinking and partying for once you're on the line and bored at the crashpad. Definitely get some relaxation time in, but only after the studying is done, and make sure you leave enough time to get a good night's sleep each night.

2) No matter how much you learned at your jet-transition course, you don't know more about the RJ than your instructors. Be humble, try to keep your mouth shut, and learn. As a side note to this, nobody cares about stories from your previous job or your previous airplane, especially if they start with "Well at ____, we did it xyz way.."