If your in compost run a wet/dry cycle. You gotta let the compost nearly completely dry out before watering again (not so much to cause the compost to come away from he pot). Then you can't really overwater if you drain your excess from the pot. To know if the pot is dry, test the weight of a dry pot. Lift it up all the time to see what it weighs. A week doing that and you should know what a dry pot feels like.
That should solve your watering problems. Once a pot is full of rootmass it should need watering every few days depending on the size of the pot, conditions in the room and so on. If you test the weight of the pot it's unlikely you'll kill plants through overwatering.