What drives people? If you can tap into the intrinsic motivation of people you have the most powerful engine you can think of to move a project forward.
The following stepping stones form the path of motivation. They are not in a specific order. Each project will pick and arrange them in a way that is suitable to them.
Does the project solve a real problem? Does it have tangible value to some audience? If the answer is yes this is a huge motivator for users and contributors alike. Of course many problems already have solutions, but often they are not open, or it's difficult to find or implement a solution. This is where it becomes interesting.
One way of looking at it is the "Scratch your own itch" perspective. If you solve a problem which is interesting to you, you do solve a real problem and you provide value to your audience of one. Chances are that there are others who have the same problem and would also benefit from a solution. If you open up your solution you can find them. That's how your audience grows.
Communities can feel like herding cats. People come and go driven my their own motives, they are driven by their own motivation. But communities are also a strong filter, because of the same reason. If the project has an identity centered around a shared vision it will naturally attract those where the vision resonates. You get a group of like-minded enthusiast. This is a powerful driver.
Often projects don't have organizational boundaries or other external factors which keep people together. So it's especially important to make it visible what serves as focal points and a shared vision can be one of the strongest and clearest drivers here. This can be explicit but it often also is implicit in the culture and a silent agreement.
A process to identify and formulate a shared vision can be helpful, although it also can be painful, because discussion about visions tend to be harder to conduct in a productive way than those about concrete technical topics.
- KDE's manifesto, vision, and goal setting process
Everybody likes recognition and appreciation. Open source provides opportunities to get that, because you can show your work to the world and can interact directly with people for whom it is useful.
Open source can be a way to build a reputation. Open source contributions are the new CV.
Proudly signing your work can be a good practice.
Lots of technical people like to geek out over certain technology. That can be a great strength because you get people that are enthusiastic, go deep, and are experts in their field. Providing a place for this can create strong connections of like-minded people and lead them to produce great results.
Be aware that it also can turn into a weakness if it becomes dogmatic and people stop being open about things outside of their comfort zone.
- KDE and C++
Open source communities can be an ideal place to learn. You are surrounded by other like-minded people. You have access to the experts, the authors, the maintainers of the software you work with. You have short feedback cycles and have the freedom to experiment but also to ship production-grade code.
Using an open source project instead of some artificial exercises to get into new technology or domain or just to try something out other people care about deeply, all that can be a very motivating and rewarding learning environment. Learning by doing and giving the results to others.
Projects which nurture this learning environment can be very attractive for eager contributors.
- Literally a learning environment: Exercism
Running an open source project is the long game. Sometimes it takes years to build something relevant. Sometimes it takes years for a relevant idea to sink and be recognized. The good part is that you often do have the time. If it's driven by volunteers, if it's your side project for fun, if it's the playground to hone your skills, then there is no need to rush, no investor to please, no boss's instructions to follow.
Having people in a project who have the persistence to follow a path for a long time because they believe it's the right thing to do is invaluable. It provides direction, motivation, and last but not least it gets work done.
Take good care of such people. Don't let them burn out.