Contributing to a on open source project is not an easy thing. Especially when you don't know where to start with. Most of the time, we encourage developers to build their own application for Cozy. It gives them ownership on the project and offer them an experience in writing a full web app with Node.js. But some of the contributors just want to contribute to already existing projects.
To make it smoother to contribute to the core applications, we recently set up a new label on all our Github repositories. It's named "Good For First Contribution". It shows which tickets should be easy to solved. It can be related to a bug report or a feature suggestion. If additional help or details are required, we can provide some to you.
Here is the list of opened tickets labeled "Good For Contribution" (you need to be connected to your Github account for this link to work).
NB: We offer coding mentorship for these tickets.