I have been working on robots from couple of years and after graduation I made a course that contains all the ROS essential you need to work using ROS.
This course is not just simulation Implementation on hardware as well I will be Using Cheap Robots (any one can buy) to be controlled by ROS , including raspberry PI , esp-8266 and 2 wheel plastic car with sensors
After this course you can work with ROS so easily and will start making your upcoming robotics projects powered with ROS.
packages used are
Find Course on this --> !LINK!