Welcome aboard!
I also got started with SH3 last fall and have found these forums to be invaluable. There is so much information here that it's hard to tell anyone where to start, but if you're interested in modding your game the SH3 Mods Workshop forum might be a good place to poke around in... some of the major mods have threads that are stickied at the top of the first page and the other current threads will probably give you a good idea of what's going on with modding in general.
There have also been at least a couple threads about "must have mods" that you might find interesting, can't remember if they're in that forum or in the SH3 forum... but they're there, and they've been active recently so you shouldn't have to look too deep in the thread listings to find them. And do check out both forums as mods are often discussed in the SH3 threads as well.
And if you want to start a thread on the topic of what mods are popular, or have a particular aspect of the game that you'd like to alter or enhance, just pipe up with your questions in either forum and you'll no doubt get plenty of feedback and suggestions.
