I set up a recurring monthly donation to PATH - People Assisting the Homeless. I started giving them the money I don't give directly to the homeless years ago. I will buy people food or gas, I've been approached at gas stations and asked to put a bit in a vehicle. If I buy someone food I try to sit and eat with them. I always try to acknowledge them too, because too many people turn away.
I have never been homeless, but I have seen how they are treated. As soon as you sit with a homeless person you see it. Everyone who walks by happens to be looking away. No one makes eye contact. Everyone treats you like you aren't there. And some are openly hostile and negative. Judgmental. And fear.
Even if you're just sitting on a bench.