From my experience teaching, I know that some folks love shortcuts and others much prefer to use menus. But even if you are in the second group, you will find that learning and using just a handful or so of the most important shortcuts will really speed up your Lightroom experience. I dare say, you will not go back!
G takes you to the Library Grid view
E takes you to the Library Loupe view
D takes you to the Develop Module
Tab hides and reveals your left and right panels
Shift-Tab hides and reveals both the panels and filmstrip
hides and reveals the filter bar at the top.
0-5 assign 0 to 5 stars to your image.
6-9 assign colors to your image.
B assigns the selected image to the Quick Collection
If you are really into shortcuts, in Lightroom go to Help>Library Module Shortcuts to see a list of many more.