Make sure you're patched up to 1.4b. Go to the ubi site and download the correct patch. When you install it, don't worry when it says you are installing 1.3... It's a minor oversight by the devs.
Get the latest free IUB mod on
www.u-boot.realsimulation.com. Also, there are more mods on this site if you ever want to browse around.
When you finally get around to playing the game, definately start in the Naval Academy. Watch those tutorial videos too - they explain a lot of things.
Umm... There are more tips but these are off the top of my mind.
Oh, and definately stay in contact with the sub-sim forums. There's always something interesting going on or a new mod being released. The community is always very active.
And this thread is your friend:
http://www.subsim.com/phpBB/viewtopic.php?t=30638 It's a list of most of the mods ever made for SH3.
Good hunting over turkey-day!
Marhkimov.