Are there certain side quests which must be accomplished before completing steps in the main quest?
Are there side quests which would lock you out of doing other side quests?
Are there certain side quests which must be accomplished before completing steps in the main quest?
Are there side quests which would lock you out of doing other side quests?
According to the answer posted on this question, and the article mentioned in the same question:
The player can make a lot of choices about the main character's story, but how much can we affect the world around us? There aren't a lot of destructive branching paths in the story that lock the player onto a certain path or close off things in the game. Rolston used to think that forcing characters to make these kinds of choices was innovative game design, but he now sees them as too limiting. There are lots of choices in the game, but the consequences of the choices won't lock the player out of content. Players will be able to complete all the faction questlines in a single playthrough of the game if they so choose.
It is possible to lock yourself out of faction quests, the key in the quote provided by Tristan is "if they so choose" (emphasis mine).
As stated here you can lock yourself out of the balance of a faction's quests
through betrayal ... if you betray your faction you will be locked out of the remaining faction quests.