Ok, I know, there are several things you need for proper plant care. But 95% of the time when I talk to people about why their plant is dying, it's the same problem.... OVERWATERING!
So if I could give anyone who thinks they're a brown thumb one tip, it is to water less often. You still want to give it a good soak, but then let the soil dry out between watering. You want the top inch of the soil to do dry. And if you're not sure, wait a few more days.
Plants have a much easier time recovering from under watering than over watering. This is because overwatering can rot the roots and create irreversible damage.
It can go against our instincts when our plants look sad and we just want to love them, but try watering less :)
P.s. The #2 problem I see is not enough light, so if you're definitely not overwatering, try that.