Do not forget that harvesting is all your current position to your Dominators. I believe the current range is listed at about 2 kilometers, though it feels like that was tightened up recently. If you have a relatively secure zone (meaning you can harvest 3 or 4 times a day easily before you get overwhelmed) then set up your Dominators, Wards, Spirit Catchers and Beacons. If you have access to multiple Gateways, then split your available Dominators between them as you will gain more points per harvest that way (the more Dominators targetting a Gateway, the less energy each Dominator receives). The Gateway distance doesn't matter, just your proximity to your Dominators.

If you have multiple gateways within your range but cannot see them all from one location, you might want to learn to leapfrog using Dominators or a friend so that you can setup a trail going between them. Unfortunately, if you do your homework well and build a safe camp, others will use it so they can go warring on the enemy. Or there are other lower level mages that live nearby and will leach off your energy. If you are the high level in the neighborhood, it is well worth investing your mana potions into your Realm. Take ownership and you will gain additional energy per harvest of your Dominators in the area. If you are dilligent about your timing, you can stay near the top of the leaderboard by doing a quest or two when you do your harvesting.