So, I've unlocked a few Dragon Age achievements. I have some tips for those who may want to avoid multiple playthroughs.  
 1. In orzammar, it will ask you to choose between two different guys. After you preserve or destroy a certain something in a place filled with lava, save your game. Then, proceed to the choice and choose who you would not have chosen, achievement unlocked! Then, load your game and choose who you would have chosen, achievement unlocked!  
 
2. Max out Persuasion ASAP. A few achievements can only be accessed through 2-4 points in persuasion.  
 
That's it for now. Good luck!