Paid Support for Indies
Paid support is a proven business model for developers of open source software. There are two basic steps:
Develop and release your open source project as you usually would.
Advertise your availability to provide paid technical support for the project in its documentation and Web presence.
Sign support contracts with paying customers.
Paid support has worked for companies large and small, young and old, especially in combination with other models, like paid development and public-private licensing. Cygnus, later acquired by RedHat, pioneered the model at scale. But many individual developers do well by selling support, too.
You can make your open source software available under any open source license.
Support contracts typically provide recurring revenue, rather than one-time payments.
Answering support requests takes time from software development.
Selling support creates a disincentive to improve documentation.
Others can compete with you by providing support for your project.