Update CONTRIBUTING.md to include PR/coding practices (#1257)

CONTRIBUTING.md

@@ -23,18 +23,18 @@ accept your pull requests.
 
 1. Submit an issue describing your proposed change to the repo in question.
 1. The repo owner will respond to your issue promptly.
-1. If your proposed change is accepted, and you haven't already done so, sign a
+1. If your proposed change is accepted in comments of the issue, and you haven't already done so, sign a
    Contributor License Agreement (see details above).
-1. Fork the desired repo, develop and test your code changes.
-1. Ensure that your code adheres to the existing style in the sample to which
-   you are contributing. Refer to the
-   [Google Cloud Platform Samples Style Guide]
-   (https://github.com/GoogleCloudPlatform/Template/wiki/style.html) for the
-   recommended coding standards for this organization.
-   1. Shell scripts should follow the [Google shell style guide](https://google.github.io/styleguide/shell.xml)
-1. Ensure that your code has an appropriate set of unit tests which all pass.
-1. Submit a pull request.
+1. [Fork](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo) the desired repo, develop and test your code changes locally.
+1. Raise a pull request.
+1. Assign reviewers who can then trigger presubmit integration tests with comment `/gcbrun`
 
+## Coding Practices
+1. [Write small PRs](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/getting-started/best-practices-for-pull-requests#write-small-prs), this helps reviewers to provide feedback and reason why something is changed. Try to keep changes < 30 lines for modifying existing init actions. 
+1. [Provide context and guidance](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/getting-started/best-practices-for-pull-requests#provide-context-and-guidance) in the title/description.
+1. Squash commit messages into final one while merging to remove intermediate changes, to keep commit history clean.
+1. Ensure that your code adheres to the existing style in the sample to which you are contributing. Shell scripts should follow the [Google shell style guide](https://google.github.io/styleguide/shell.xml).
+1. Ensure that your code has an appropriate set of unit/integration tests which all pass.
 
 ## Best Practices