I'll typically help with food. Rarely cash these days. It's just too hard to tell where the money really goes. (Unless the donations are through an organization)

Short anecdote - A friend met a homeless man on Haight St who in exchange for a burrito showed him some of his wild world. The man ended up taking him to an abandoned warehouse covered with mattresses and needles. The man opened up a bit and told my friend that when he asks for money, he doesn't care so much if people don't give it to him. But what gets to him after a while is how most people won't even acknowledge his existence when he asks. He said he understood if people said no, but he appreciated at least being told no or even simply looked at.