This is a major issue amongst retired players. Generally, the guys that make big bucks end up doing OK. If they don't, you usually hear about it in the news (Mike Modano or Jack Johnson, for example). But there's a long list of players who had decently long careers in the NHL making OK money, or even more journeyman types who never banked the big bucks, that find themselves in real trouble during retirement.
One of the biggest issues is "who do you trust". NHL players - and celebrities in general - are susceptible to the "hey, I've got a friend who has a great investment opportunity" for you gig. A case in point is the Bear Mountain Golf Resort:
Current, former NHL players lose more than $13-million in resort deal
There were some guys who got absolutely ruined financially by this, even worse than what the article illustrates, and this is just one example that made the news.