To access the hashes mentioned below you can run git log on whatever branch and then copy it.

git-reflog may be useful for seeing all steps you've made previously.

Reverting Commits

Better for using on the master branch, maintains commit history

git revert {commit hash}

---

Better for using on other branches, doesn't maintain commit history

The Soft param returns the files to the staging area

The Hard param returns to the commit and ignores all the changed files

git reset --soft {commit hash}
git reset --hard {commit hash}

PS: It may be necessary to use the --force param for pushing to master branch when having different commit histories

Changing Previous added Commit

Amend is recommended for separate branches or changes that have not yet been pushed to the remote

git commit --amend 

Cherry Picking Commits

Used for picking specific commits from another branch

git cherry-pick {commit hash}

Committing specific hunks of a file - Interactive Staging

git add -p 
git add --patch <fileName>

Legend

y Stage this hunk for the next commit;

n Do not stage this hunk for the next commit;

q Quit; do not stage this hunk or any of the remaining hunks;

a Stage this hunk and all later hunks in the file;

d Do not stage this hunk or any of the later hunks in the file;

g Select a hunk to go to;

/ Search for a hunk matching the given regex;

j Leave this hunk undecided, see next undecided hunk;

J Leave this hunk undecided, see next hunk;

k Leave this hunk undecided, see previous undecided hunk;

K Leave this hunk undecided, see previous hunk;

s Split the current hunk into smaller hunks;

e Manually edit the current hunk;

? Help

Deleting branches

Locally deleting - You may need to change branches before deleting the one that you want

git branch -d branchName

Remote

git push --delete remoteName branchName

Example: git push --delete origin myBranch

Searching for commits without the hash

For searching in the log section (commit message)

git log --all --grep='commit message that I want to find'

For searching the content inside a commit

$ git grep 'commit content inside the files' $(git rev-list -- all)

rev-list documentation

For searching commits in the log with regex match on the content

git log -G 'content that I want to find'

or 

git log -G 'content that I want to find' --full-history --all

Git Stash (WIP)

Credits:

Git na Vida Real

Interactive Staging - Legend Section

Additional resources and links

Git Official Doc