All of the best leads I've had as an independent developer have come from folks I met briefly at networking events or on other contracts.

As a rather introverted person, it's hard for me to go to a lot of these, but going to ones where there's interesting things being discussed either in tech or business has been worthwhile. One of the big lessons I've learned is that everyone's startup is mediocre until it turns out not to be. Being polite and helping folks at these things have helped me more than assuming folks are wannabes.