Wish I could help out. I was in the same boat as you two years ago when I started using NC (have never touched Expert though). All I can add is that it just takes lots of hands-on. Having a good understand of Pro itself is essential. All (one!) of the tutorials I've read border on useless.
I think you should subscribe to the manuf group Exploder at ptcuser.org, you will find lots of help there. Otherwise, it is mostly being able to make the right choice of sequence type right at the outset so you're not banging away trying six ways to Sunday to find one that works.
What type of parts are you making? Molds? Prismatic?