There is so many tips under the New Recruits section that if you just picked a random thread and skimmed through you're bound to learn something new! Everyone has their own style and way of doing things which is a great way of learning different processes and getting a perspective on how other people think through the common prop building problems. No method is "correct" since there's lots of ways to skin a cat, some methods are just more efficient and some might be better suited to your tools, workspace and experience. Poke around, do some reading and ask questions on threads to get insight on why people are doing things certain ways and you'll build that cosplay knowledge crazy fast.
If you want the cliff notes version of a few of the more common approaches check out the
Tutorials Index because there's just so many different things there!
Also, what sort of crafting have you done before and what kind of costume do you want to make?