When to amend/squash commits and how to maintain a clean PR

I always like to improve the development process with the git and a strong believer in the clean code.

Something which I always insist during my PR review is - maintain the clean git history by avoiding the unnecessary indivual commits. 

Broadly, we can follow these 2 rules:

1. amend/squash commits if they don't add semantic value to the PR
2. Always rebase the PR before you push to the server

Below article exactly reflects my thought on this.

https://github.com/mockito/mockito/wiki/Using-git-to-prepare-your-PR-to-have-a-clean-history

Other nice articles on this:

https://www.atlassian.com/git/tutorials/rewriting-history

https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History