Gmail Quick Keys
If you are someone who relishes in the quick key shortcuts that you know (command + c = cut, command + v = paste, etc.) then you may be interested in the list of quick keys that I found for Gmail. You can pull up the list right in Gmail by clicking shift + question mark and an overlay will appear with them all. You may also need to turn on the bottom section of the shortcuts depending on if you have used them before or not.
I also went ahead and created a document with all of the shortcuts in it, which you can find on my "Guides & Tutorials" website by clicking here. Like many shortcuts, it will likely take a bit to remember them, but it can certainly make cruising through your email pile quicker if you know them.