Barch (barbarians and archers) is by far the most efficient strategy for farming. The troops are quick and cheap to train and loot can be taken with a small or large portion of the army.
Almost every farming strategy has some Barch in it and experimentation can be done by adding a few troop types to normal Barch attacks (a few giants for instance).
Get to know Barch as a "go to" strategy for quick sessions and the skills needed to do more complex farming. Barch can be done at all TH levels up to at least TH 9.
A few things to know about Barch:
- Outside collectors are the main source for Barch attacks, get to know what full collectors look like.
- Take a few wallbreakers as well for the times when pushing a bit into the base is opportunistic.
- You can train most of your army then start searching. Stop searching to pick up more Barch and continue searching, making runs quicker.