Of course this applies online too! Screens don't carry the emotional resonance of faces, which means an intentional kind approach is even more important online.
Online and offline always try to:
Think about others' feelings.
That complex set of reactions, thoughts, and feelings that goes on in your head happens to everyone else too.
Hold judgment and try to put yourself in the place of another.
Before you condemn or mock someone, think of how you'll feel when it happens to you.
Listen to what people have to say.
One way or another, everyone shares their emotional states. Attention and care can mean the world to someone.
Try to understand others' points of view.
What do they mean? Why do they think that way? You learn more with generosity.
Remember that not everyone reacts to things in the same way.
And that your way isn't more normal, the standard, or the right way.