Welcome!.
I'm in the same u-boat as you , I started just over a week ago.
I cant believe I missed this one , considering how old it is now.
It's a great sim , really immersive, although be warned - time will fly when your'e out at sea stalking those merchants.
I am using GWX 3.0 , SH commander 3.2 , lifeboats mod , and water/smoke mod with 16km atmosphere enabled . I thknk that's a good base to start off from.
(I would use the merchant fleet mod , but it crashes on me
)
Heres one tip for you - When leaving port for the first time , zoom RIGHT IN on the port before plotting a course, as when you are zoomed out it will not show the port layout.
On my first mission I went ahead and plotted my course and promptly smashed my sub into the harbour wall ....
Anyway , good hunting!