As Phil notes in his review, Dragon Age: Inquisition's massive scope is matched by the complicated and sometimes overwhelming ways in that it interacts with pre-existing Dragon Age canon. I've been playing it too, and even with a thorough knowledge of the previous games - and having read all of the novels and comics - it takes a little work to hold Thedas' complicated history in your head all at once.
This is particularly true if you're just getting to grips with Dragon Age Keep. Rather than import saves directly from previous games, BioWare have opted to allow you to configure a world state via an online application. This helps you to resolve plot holes, ensure that every decision is registered correctly, and even change a few if you're not happy with how things went. That said, configuring Keep with a fuzzy memory of Dragon Age isn't easy. For that reason, we've put together this extensive guide to every decision it asks you to make.
Needless to say, this is going to be a long article and it will involve heavy spoilers for Dragon Age: Origins, Dragon Age 2, and their DLC, but no spoilers for Inquisition itself. The hope is that it'll help you establish your world state just-so in time for Inquisition's release, whether that means reminding yourself about decisions you made back in 2009 or configuring a new save file based on the Warden or Champion you have in your head.
If you'd prefer to receive the guide as a video - or even just listen to it like a podcast - you can find that right here:
Skip to specific games by following the links below.
This guide follows the approximate ordering of the choices in Keep itself, not the narrative arc of the games. That said, the order of the tiles is a little arbitrary and sometimes it'll be necessary to jump from topic to topic.
Next page: Dragon Age: Origins, Warden, Companions