Plants are people too.
Try to love them like you would a friend,or a pet. You wouldn't make your puppy drink water until he was sick would you? Talk to your plants, look at your plants, touch them. Get to know your plants. Don't expect them to give you something for nothing. All relationships are give and take. When you give your plants the attention they need, they will happily reciprocate by giving you beautiful green goodness to look upon. They will gladly fill your your life with tranquillity and peace.
Plants should be green and lush, supple to the touch. If your plants are showing signs of fading, flaccidity or feebleness, you can usually perk them up by misting their foliage for a few days. Also adding some liquid fertiliser to their water will help them stay tip top; follow the instructions on the packet.
Moss is especially sensitive to contaminants. If you are spraying fly spray, air freshener, perfume, hairspray etc. in the room where your moss lives then expect your moss to die sometime in the near future. This is much more of a problem if your moss is on the outside of a kokedama or if your terrarium does not have a lid.
Please read the specific care instructions for your particular baby.