Your thumb is greener than you think! Overall, your Zebrina is very healthy.
The pale leaves are not caused by too much light or by dry air. Those are mostly older leaves that die back naturally as they age. A few instances of improper watering can hasten the paling of some of the those leaves. Pay close attention to the watering and water thoroughly as soon as the surface of the soil feels nearly dry.
This is a vining plant that will need regular pruning if you want to keep it full and compact. Otherwise, older leaves will die gradually from the soil end up and you will end up with long bare vines with healthy leaves only at the ends of the vines. So resist the temptation to let the vines grow ever longer.
Any vine that has lost several leaves already is a good candidate for pruning, Cut such vines back to the second or third node above the soil. New growth will then emerge from the node closest to the pruning cut and fill out the plant. The tip cuttings can be propagated easily in water or damp soil.
