[Question] What are effective ways to help Ukrainians right now?

It happened, Russia has now launched a full-scale attack on Ukraine. This might be the beginning of a major war in Europe, possibly also beyond Ukraine. I feel like a lot of people want to help, but how? This cause is certainly not neglected, but I wonder if there might still be any effective interventions. Curious to hear your thoughts, please add ideas and upvote those you find worth investigating more.