Victoria's interesting post, ended with a very important question;
How do you help the friends in your life without overstepping your boundaries?
In my culture, this wouldn't be much of a problem. Everybody's problem is everyone's concern, even a stranger. In fact a Yoruba adage says "One person births a child, the entire village trains the child" literally. So there wouldn't be much concern about "overstepping boundaries". But, that was then, globalization/civilization (read western influence) have reduced all of that to a bare.
(Some of) My answers would be...
#1 Take time and discuss all the possible scenarios/outcomes of their decisions. This would require long (and maybe boring) talk, but i think it signals your intentions. It shows you are actually thinking about them. Hopefully they see it that way and respect you for it.
#2 Tough Love (that's what people call it). This is talking your friends and taking actions that helps them make what you think is the best choice for them. It's like you're dragging them to do it. Hard one, requires some level of permission. I don't often suggest this, but if you have such permission and you're sure of the outcome. It's worth the risk.