Pots without Saucers: This can take a little more time but tends to work just as well. If the pot is too big then put in in a large plastic box/tray. Fill it with water and give it time to let the water soak up through the soil. Remove the pot from the water once damp on the top. If the pot is small, a sink works well. Place the pot in the sink and fill with water until the water is about 1 inch below the soil level. It will quickly soak up through the soil and show dampness on the top. Remove from sink when damp.
Note: You do not want the pot sitting in water for long periods of time as the soil does need to drain.
Watering plants from the bottom is crucial in maintaining good oxygen levels and good soil composition in the pot. It may seem harder and annoying but it really does pay off and always feels like the growth rate is improving for some reason.
Pots in Saucers: If your pot is in a saucer, it will be easier. A good way to water from the bottom is to fill the saucer as high as you can with water before it overflows. This allows the water to slowly absorb up throughout the soil. If the top of the soil doesn't look damp once all the water is gone, fill the saucer again. Repeat this until the soil looks damp on the top.