Hi, i was just starting the game and figured out that i dont want to lose dozen of hours beacuse any fatal bug that i was unaware of, like it happened to me on fallout 3 so i was hoping you can tell me when/where exists a danger of a fatal bug and how should avoid it
thanks a lot

You might want to turn off autosave, else your game will save every time you go into a new area,every time you sleep, every time you enter a building, every time you complete a quest... and so on. I've heard that made some peoples games crash alot.
Save often, and have multiple saves, dont just pile everything into one save file.

If you encountered the various bugs related to this, it's not usually "fatal" (that is, you could still complete the game), but since you're not on PC, I'd advise not wearing any faction armor. Ever.