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Finally, Git Best Practices is an excellent page with tons of information, overview and links to other good resources about best-practice usage of git.
Git Merge Strategies
Git has many "strategies" you can use while merging. Read the following carefully:
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This is a compilation of some potentially useful git commands and/or aliases
1) Command Line commit graph
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Check out this blog post: http://www.programblings.com/2008/06/07/the-illustrated-guide-to-recovering-lost-commits-with-git/
Not really a git trick, but a github convenience. Repositories on github can have their default branch specified. This is useful to reduce drag and prevent worry, by making github automatically select the correct branch for a pull request to go into.
Simply go to your github repository's page and click the admin link (hint: you need admin privileges), right near the top of the page there's a setting called "Default Branch".