How can I make a difference in the world?

I'm 15 and the state the world is in saddens me. I have always been very pionate about helping others and helping to make this world a better placeand just generally helping others but I honesly don't know where to start. Living a relatively sheltered life but knowing how terrible things are for others and not knowing what to do is incredibly frustrating . I would love to donate money but I don't have much.What other things could i do? (I have a great love of animals) I'd really appreciate any help! Thanks in advance!