One day I'll do a Magit video but since there are already some good ones out there I thought I'd share a couple of other great git related packages.
The first is Git Gutter which adds markers on the side gutter of your buffer so you know what's changed since you're last commit. I pretty much use it exclusively for that visual but it can also be used to cmmit and revert individual chunks of your changes.
The second is Git Timemachine which lets you move forward and back between commits.
The video demos both.