You may not have noticed that you get three daily bonuses for completing faction missions (see image, top left).
This means that for the first 3 faction missions of the day you will get 200-300% more experience points (depending on the area influence). If you happen to have missions that give little XP, you can cancel them and wait for better missions. Every 30 minutes you will see new missions. In the upper right corner of your mission overview (as shown in the picture below) you will see a small hourglass that shows you when the missions will be updated for you.
This daily bonus counts for the complete map and not per zone.