Books could be written about this subject.lol The easiest way to explain it, is to explain that overwatering, is a failure to let the soil dry sufficiently(to approx 70-90% dry) after a thorough watering,(to the point of a little runoff, or very close to that) and isn't based on the amount of water you've given your plant, during that watering. If your just giving your plant minimal amounts of water, when you water them, you're probably underwatering, and if you're watering them all the time, keeping the soil constantly wet, you're overwatering. Soak them, let them dry out, soak them, let them dry out, etc..... Do that, and you won't have to worry about it, unless you let them get too dry, in which case, they will quickly get droopy, as soon as they pass a certain point of dryness. If that happens, it's not a biggie, you just water them, and they'll perk right back up. Catching them just before that point, is what your looking for. Get that right, and you'll be good to go.
Typically, damaged leaves won't recover.
