OK so ever since the .dll/Optimus fix I haven't encountered any bugs other than occasional wacky enemy AI. I've heard some people say that they've encountered gamebreaking bugs throughout the game so I'd like to know what I should avoid until a patch is released.

My savegame from Oct.19 (opening day) doesn't work anymore.
Patches seem to have broken it, or...?
So to answer your question, what should you avoid, you should probably avoid playing for a few days.
I wish I did, heheh...
Regards

Avoid playing and you won't see any bugs

Seriously though.. just enjoy the game. If you're one of the fortunate, game on.
The best weapon against future bugs is to save your game frequently. With hard saves, not quick/autosaves.

Avoid playing "Come Fly With Me" quest if you haven't already finished it, it was known to corrupt all subsequent save files for some people, but not all.

This is after the current patch.