First off, welcome to the forums!
The best advice I can give someone new to the hobby, is to read, read, read, and then read some more! Learn from what other people have done, and understand why their builds look so great, and how to avoid mistakes that they have made. I would strongly recommend checking out the "elite builds" (I believe that they can be found in the costumes and armor forums, as they are very well detailed and can show you a lot of tricks and tips!
The faq threads and stickys are also a good place to read.
All of that said, there is a ton of good information in the new recruits forum, so I'd just start clicking on threads that look interesting, and reading them from start to finish!
Good luck with your prop building!