How to pick an open source project to join? [closed]

Question

I am interested to join an Open Source project using .net; I would like to be able to choose between a mature project and a starting one, as well as other criteria. What do you suggest? (specific projects are welcomed).

Later edit:

I am disappointed by the arrogant comments / answers received so far. Picking an OS project to contribute to is not a simple task. I have spent many hours today doing this. My experience shows that:

• few projects advertise how to contribute to them
• few projects even let you contribute
• a lot of projects expect you to contribute by writing docs and answering user questions
• there are many projects that are "dead"
• not everybody uses OS software written in .net - it is a starting community - so the criteria "contribute to the project you use" is not useful

I believe this question is far from being answered. I have carefully read the related questions, there are some good points there, yet nothing truly revealing.

Answer 1

The obvious criteria would be to pick a project in an area that interests you.