I'll play along!
1) What was your first 501st build project?
A RotS clone trooper. Start with the super hard stuff
2) What specific aspect(s) of the build posed unexpected difficulties? Fitting was my big deal. Since everything needs to be proportional, you have to kind of fit it all as you go, not just piece by piece. Measure twice, cut once as the saying goes.
3) Who/what were your most valuable sources of information utilized during your build? I was a forum junkie. I didn't reach out to my local 501st. Now, as a GML, I wish I would have. Would have made life easier.
4) What are some common pitfalls that newcomers such as myself often fall prey to when beginning their first build? Impatience. This stuff takes time. Don't rush anything, because it means you might have to do it all again. Need that paint to dry for 48 hours? Give it 72. Think you've sanded enough? So down a grit and give it one more. Take your time.
5) What would you do differently about your first build, knowing what you know now? Nothing about the build, I just wish I would have reached out sooner.
6) (Optional) Anything in particular about a R1 DT build that I should cognizant of in terms of complexity, fabrication, acquisition, etc? Since I have nothing to compare it to, I have no idea if this is a challenging first build or not. The biggest challenge is the diversity here. There are so many different types of parts. My clone was all plastic, so go go go. With my snowie, I had to learn to sew to make pouches and such. This has some of that same diversity - plastic armor, rubber parts, cloth gaskets, shoe covers, etc.