Always prioritize matches at the bottom of the board. This creates cascades (chain reactions) that clear more tiles automatically, often forming power-ups you didn't even plan for.
Replay older levels to increase your star count. Earning three stars on a level contributes to treasure chests that often contain diamonds. Fishdom Hack
Active teams are essential. Not only can you request lives, but team competitions provide significant group rewards including diamond prizes. Always prioritize matches at the bottom of the board