There is a show I forgot the name of that the rich move into poor areas for a week and see what is happening and help out (the secret millionaire I think?) and either it was the same show or a similar one that did it via living on the streets too even if America the same concept can apply for doing things here or elsewhere that would be a good thing to check out. You can already help out by volunteering in kitchens or giving out soup on weekends at special events etc, never too young to start!
And yes, I realise that not all homeless are grateful and can be downright rude but the majority of them you come across you may not even realise are homeless as they blend in due to issues about being seen homeless. When I was with my ex in Norwich in 2010 or so there was a guy who we approached and we ended up getting him a sandwich and bottle of water and he was extremely grateful, we stayed with him for about 45 minutes and met some of his friends who did not ask us for anything and explained how people had helped them or how they are clearing things up and able to get a roof over their head or job