Welcome Chris! Sounds like you are doing all the right things to develop your talents. For mountmaking, a colleague attended a week long seminar at Benchmark and it was invaluable - expensive too. Are you part of the mountmakers forum?

As far as your questions, I'll do a couple:

What has been your greatest asset?
Staying intent on improving methods. Museums are insular work environments and it's easy to get stuck doing things the same way that someone taught you. Being involved in groups like this is great, asking questions of other museum professionals in your area of from different disciplines can be helpful, and the private sector in related trades can't be overlooked since they may employ more effective skills to get work done more efficiently as opposed to museums that aren't as bottom-line driven.

What has been your greatest hang-up?
Staying focused on projects that you have reservations about. Whether it's the subject matter, the design treatment, lack of support, questions about the value of an exhibition - it's a challenge (as it would be with any job) to keep the interest and passion for the work. That's where my answer for the first question helps me: be inventive, explore different angles for accomplishing tasks and problems, keep learning and developing your talents. If you're like other preparators, you're into tools, equipment, hardware, and customizing any and all of that to make things work for you, and that's what can sustain you through otherwise unrewarding projects.

Cheers, and good luck!