The finger test
Push a finger a few centimetres into the soil near the plant, away from the stem. Feel for coolness and moisture below the top layer, where the roots are actually working.
Lift pots when you can
With practice, a pot feels noticeably lighter when it has lost water. This is especially helpful for small containers that change quickly.
Look for patterns, not one clue
Combine the soil feel with leaf posture, pot weight, recent rain, and the forecast. One clue on its own can be misleading.