Lagwar has a sucinct and accurate guide to zone domination.
If you read nothing else from lagwar know this:
The optimal method:: This is NOT meant to maximize renown gained from BFO’s and keeps, this is meant to capture the zone as FAST AS POSSIBLE. Take both of the keeps as close to simultaneously as possible. Guard them well, camp the opposing realms warcamp, or queue scenarios, but DO NOT LOSE THE KEEPS. Now that keep doors reset if they aren’t broken down after 20 minutes (20 min not in combat) it is very possible to successfully chain defend keeps. Once you’re at an hour and 15 minutes of holding the keeps, go out and take all the BFO’s, try to capture them as close to simultaneously as possible as well. Now if you successfully hold everything, the BFO’s will finish their zone domination counter at approximately the same time as the keeps. Start to finish it will only take 2 hours to flip the zone with successful defense.