A selection of initiatives and organizations where you can donate:

Libereco - Partnership for Human Rights e.V.
This is an independent German-Swiss non-governmental organization that works to protect human rights in Ukraine and Belarus.

German Red Cross

Under the following links you will find a selection of further information on how you can help the people affected by the war in Ukraine directly here in Berlin: 

@ukrainehelpberlin

Network Berlin Helps

Elinor - shelter for people from Ukraine