There are several organizations that do extensive research and analysis in order to give guidance on donating to the most effective charities. Here are some sites where you can find recommendations for your giving:
The Life You Can Save: https://www.thelifeyoucansave.org/Where-to-Donate
Giving What We Can: https://www.givingwhatwecan.org/top-charities/
The Open Philanthropy Project: http://www.openphilanthropy.org/
Since effective altruism is an non-speciesist movement, we feel that animal causes ought to be considered.
Animal Charity Evaluators: https://animalcharityevaluators.org/