1. Filter projects by two criteria: do I know the stack? Am I a user? If you don't know the stack or aren't a user, you'll find the project to be inaccessible.<p>2a. Identify a bug or missing feature. You may do this yourself, or you may look at the issues list for the project. Fix the bug or add the feature.<p>2b. Or, if you prefer, you can write tests. Many projects have less than 100% test coverage, or their tests haven't been updated for the latest version. Writing tests for alpha or beta versions is <i>really</i> helpful in getting those versions finished.