I received a cutting last year and it rooted. I left it alone and then started watering regularly. I noticed a few days ago the top part of the offshoot was turning a lighter green. I stopped watering it and moved it to a sunnier place. Will the plant be ok? How do I know when to water it? Any and all advice / resources would be appreciated. David Fine
Here is a link to an article that will tell you how to care for them:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/epiphyllum/epiphyllum-plant-care.htm
Keep the top 1/3 of the soil damp but not saturated. Too much water will kill the plant. They prefer morning sun or filtered light. If you haven't fertilized the plant, see instructions in article above.
You also may find this article on browning leaves helpful, as there are several possible causes for the change in your leaves:
https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm