This afternoon I stumbled across a GreyWardens.com story that ran back in December 2010. While long, it is a good guide for those who plan on importing an old save into Dragon Age 2, but didn't take the consequences of their character's actions into consideration last play through. Since I generally take those kinds of things into consideration anyways it is not going to affect the way I play. If, however, you are more of a hack 'n slash spur of the moment type gamer, or someone who lets others guide what the "best" decisions are to make, then you might want to consider a replay of Dragon Age before DA2's launch. Important issues this article does bring up concern mods, DLC, Awakening, and side quests. If you regularly use mods that affect vanilla gameplay then this might corrupt your savegame and make the import of an old save difficult. Likewise be aware that how you played the DLC, the quests you took from the Blackstone Irregulars/Mages' Collective, or how/if you played Awakening may all alter the world you face in DA2.
Read "Dragon Age 2 – Building Your Import" Here
Image: Dragon Age Origins Blog