Hey there!
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The techniques are really simple, no matter the size of the pots. There are bunch of ways how to figure out when to water and how much, and I know it can be nerve wracking, thinking that you are potentially screwing it up
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!
First of all, you can jab your finger into the topsoil and feel if it's wet or not, that will give you an idea. You can also weight the pot by lifting it up slighly and if it's watered properly, it'll be heavy as a mudfugger
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If you want to get scientific (and maybe it will ease your mind) you can get soil hydrometer, you stick it into your soil, keep it there, and it will show you how watered it is.
It's important to know that underwatering is better than overwatering! Plants naturally go through multiple cycles of wet/dry soil and they don't mind, but if you keep watering too much too often, it can create problem such as water logging the roots which prevents oxigen from getting to the roots, up to serious problems, such as mold or root rot, fungus gnats, etc.
By how much, younger plants don't need a lot, most enjoy frequent watering in smaller amounts, but as the plant gets bigger, it drinks more, and you'll see this because the pot will be dry more often.
Keep on growing!