Watering the plant calls for your judgment. But there are a few indicators which may help you with your watering woes.
You can check the top layer of soil. You can water once the top layer of soil is dry.
The second one is by looking at the leaves. If the leaves look droopy or dull you can water the plants.
Now here’s the key. If you’re seriously clueless try by watering a specific quantity. Say for example, 100ml. Wait for 24 hours. If the plant and/or soil has dried up.. water a little more quantity,say, 120ml. Wait again for 24 hours and check. Keep increasing the quantity till the time you find out that it has optimum water for 24 hours. The indicators are that the plant (basically the leaves) look fresh even after 24 hours and only the top layer of the soil is dry.
Happy Gardening 🙂