A good starting point: Sparkfun's tutorial series

installation and setup

https://learn.sparkfun.com/tutorials/how-to-install-and-setup-eagle?_ga=1.22658875.145965626.1479945982

schematics and board layout

https://learn.sparkfun.com/tutorials/using-eagle-schematic?_ga=1.23311290.145965626.1479945982

https://learn.sparkfun.com/tutorials/using-eagle-board-layout?_ga=1.23311290.145965626.1479945982

for further reading

custom parts creation, smd, importing images and more

https://www.sparkfun.com/search/results?term=eagle

http://syinsi.com/cadsoft-eagle-tips-and-tricks/