Hi,
That sounds like a very standard set up so you shouldn't have much to worry about. The only thing to be aware of if whether you really need tags and categories as opposed to just having one of the other. If you do, for instance, you might decide to keep tags for navigational purposes, I'd consider noindexing the tag pages. By not indexing them, they won't cannibalise your category pages, but you still get the benefit of the user experience of having tags that visitors can use for navigation.
Craig