This strategy is called Town Hall Sniping. Search for isolated Town Halls and use a few barbarians and archers to destroy it. You receive 1/3 of the total trophies you can get from the defender.
This strategy is good to reach 1250 trophies (Sweet Victory! Achievement) and receive 450 gems to purchase your 3rd builder's hut.
Snipe to Crystal League (2000 Trophies) League All-Star Achievement and receive 250 gems.
Snipe to Master League (2600 Trophies) League All-Star Achievement and receive 1000 gems (enough for 4th builder’s hut!).
Snipe to Champion League (3200 Trophies) League All-Star Achievement and receive 2000 gems (enough for 5th builder’s hut!).
This strategy works best at lower Town Hall levels where search costs are minimal.
If you need inspiration, do a search in Clash of Clans called “TH Snipers” Green and Yellow clan symbol (the one with the most trophies!)