The Four Finger Fighting (FFF) is in my opinion, THE BEST FARMING STRATEGY! The other good thing is that if used properly, you can almost always get 50% on any base.
FFF: If you have 200 army camp spaces, train the following troops; 90 Barbarians and 110 Archers. Note: Spells/Heroes are not usually needed. I usually bring 2 heal spells and 1 lightning spell.
To pick a base to raid, I usually find bases with either a lot of loot in the mines and pumps or a base with lots of buildings on the outside.
1. Drop a barbarian to check for cc troops. Destroys them if need be.
2. Zoom out so you can see their entire base.
3. Using your index fingers and thumbs on both hands, deploy barbarians (In a straight line around the base. (If you keep your fingers and thumbs on the screen for a second or two, you will not need to repeatedly tap on the screen.)
4. Do the same thing with your archers and watch your troops go to work on their base. (You can deploy heroes and spells if needed.)
This attacking strategy will almost always result in you getting 50%. If you are not getting 50%, it is probably because there are not enough buildings on the outside or that they are too high level of a base for your troops.
Hope it works for you!!