So, I've been away for awhile and the page count has skyrocketed. With all these new pages has come new categories and a confusion about what had how categories work.
Firstly, what is a category? It is a means of organizing and grouping similar pages together so that they can easily be located. For the most part they function similar to folders on your PC, with a file sitting in a single folder which may be a sub-folder of an other folder. Browsing a wiki by categories should be nearly exactly like browsing the contents of your hard drive. There are exceptions and depending on how content is best found it could end up in multiple categories. Unless you know for certain that a file or category should be in more than one category then you should avoid it.
Second, categories are NOT tags. Categories define where pages are located and group similar pages together. Tags are used to help find pages with similar subjects using tag clouds or the search function. GalNet wiki doesn't have a tag cloud or the ability to make one and the the built in search functions on Wikia are far superior and can find anything you are looking for.
Third, category loops should be avoided. That is when a category is a subcategory of another category and that other category is a subcategory of the original category. If you are confused reading that then you know why they aren't good and should never ever do it and if you did understand that then you know how they work and would never do it, EVER.
Fourth, Category:GalNet is the source of all content on the wiki. Every page and category should be navigable from that category. Exceptions of course exist but unless you know exactly what those exceptions are, be sure to place your pages and categories in their appropriate places.
Fifth, avoid new categories. GalNet is getting bigger and bigger and there are over 300 categories. There were over 350 when I returned from by absence. I ended up deleting dozens of empty and duplicate categories, and several more were linked into the content tree. Anytime you place a page in a category you should know exactly where it's going to end up. Even if the category is suggested when typing it in, know where you are putting your pages and categories.
Lastly, we all make mistakes. I can pretty much guarantee that if you contribute to the wiki you are going to mess up in some way. That's fine. That is what a community is for. Something you do with be changed, or reverted, or opposed, and that is just part of a wiki. We are all working towards the same goals because we love trans-universal window into the GC-verse. The big thing, is to learn from your mistakes and take them graciously.
I hope this helps some of you better understand and utilize categories better here on GalNet. Please offer suggests below on things that should be added to this list. If we get a good version we could create a wiki editors guide.