As mentioned above, it is perfect to trust and learn much from your master and the professionals from your training company.
In addition, you should still see that you also contact other roofing masters and let them tell you what is important!
If you live in Lower Saxony, find here for Hannover a good roofer who can take you under some circumstances by the hand!
At this point, something of your own research and use is required. Many old-established roofers will be glad, however, to pass on their knowledge to the next generation.