I make a profit off every serial I do; most of them make me about what you'd expect for a first-time novelist's advance. I experiment with every model I try, everything from "pay to vote on parts of the story" to "pay per episode" to "tip if pleased." I release merchandise. I do e-book versions and hard copies when I'm done. Here's what's worked for me:
1. Have lots of free stuff. Preferably, make the thing you're selling free and monetize it in some other fashion.
2. Be personable. People like paying for someone who works hard and accepts their money with genuine pleasure and gratitude. Bitter artists who update infrequently can make money but they have to work much harder for it.
3. Make the story available in multiple formats. Most people are perfectly content to pay once for a serial, and then if they are excited about it, to buy either a physical book or an e-book version they can take with them away from their computers--
4. --however, keep your prices reasonable. If you know people are going to pay twice or even three times for something, don't squeeze the money out of their pockets. Make it affordable, or you won't make the sale and you will incur patron displeasure.
5. Finally, foster your community. Give the people who like your work a place to talk together about it. Chances are they'll like each other. They make new friends, you make new friends, everyone is happy.
Ryan's points are also good.
Please note: it took me years to get to this point, and a lot of projects published. Don't expect your first project to make you a great deal. My first project made me $400. The second, $700. It grows, but you have to write a lot, write consistently, and be willing to make it all available.